BiOLOGY 
LIBRARY 


THE  NEWER  KNOWLEDGE 
OF  NUTRITION 


THE    MACMILLAN   COMPANY 

MEW  YORK   •    BOSTON   •   CHICAGO   •    DALLAS 
ATLANTA    •    SAN  FRANCISCO 

MACMILLAN  &  CO..  LIMITED 

LONDON   •    BOMBAY   •    CALCUTTA 
MELBOURNE 

MACMILLAN  CO.  OP  CANADA.  LTD. 

TORONTO 


THE  NEWER  KNOWLEDGE 
OF  NUTRITION 

THE  USE  OF  FOOD  FOR  THE  PRESER- 
VATION OF  VITALITY  AND  HEALTH 


BY 

E.  V.  McCOLLUM,  PH.D.,  Sc.D. 

Professor  of  Chemical  Hygiene  in  the  School  of  Hygiene 

and   Public    Health,   of  the   Johns   Hopkins 

University,    Baltimore,    Md. 


ILLUSTRATED 


SECOND  EDITION 
Entirely  Rewritten 


gotfc 
THE  MACMILLAN  COMPANY 

1922 

All  rights  reserved 


PRINTED  IN   THE   UNITED   STATES   OF  AMERICA 


COPYRIGHT,  1918,  ANT>  1922 
BY  THE  MACMILLAN  COMPANY 


Set  up   and   electrotyped.     Published   October,    1918 

Second   Edition  Entirely  Rewritten 

April,  1922. 


To 
DR.  C.  EIJKMAN 

Professor  of  Hygiene 

in  the  University  of  Utrecht, 

Who  First  Produced  Experimentallj 

a  Disease  of  Dietary  Origin, 

THIS  BOOK  is  DEDICATED 


PREFACE 

The  science  of  nutrition  has  now  reached  a  stage  of  develop- 
ment where  it  seems  highly  desirable  that  its  history  should  be 
written,  notwithstanding  the  fact  that  at  present  it  is  attracting 
the  attention  of  a  greater  number  of  investigators  than  at  any 
time  in  the  past.  There  are  distinct  signs  that  discoveries  of 
practical  value  in  this  branch  of  physiological  chemistry  will  not 
be  made  so  rapidly  in  the  future  as  they  have  been  during  the 
past  seven  years  for  the  reason  that  the  relatively  simple  technic 
which  has  characterized  the  experimental  work  in  this  field  gives 
no  promise  of  bringing  to  light  further  spectacular  results. 

The  experimental  methods  hitherto  described  can,  when  the 
necessary  labor  and  money  are  expended  upon  them,  perfect  our 
understanding  of  the  quantitative  relations  of  the  amino  acid 
content  of  the  individual  proteins  and  mixtures  of  proteins  which 
occur  in  natural  foods  of  animal  and  vegetable  origin.  They 
can,  furthermore,  serve  as  an  aid  to  the  isolation  in  a  state  of 
purity  of  the  several  vitamins,  although  they  are  but  poor  and 
unwieldy  substitutes  for  chemical  tests,  which,  unfortunately, 
are  still  wanting.  The  tree  of  nutritional  knowledge  appears, 
however,  to  have  grown  to  proportions  which  reveal  the  general 
outlines  which  it  will  always  present,  and  further  researches  by 
the  methods  which  have  hitherto  been  so  productive,  can,  it 
seems,  only  clothe  it  in  attractive  foliage  and  aid  it  in  maturing 
the  rich  setting  of  fruit  which  has  not  yet  ripened  and  fallen  for 
the  service  of  man,  although  a  few  windfalls  which  have  been 
tasted  reveal  the  keen  enjoyment  with  which  the  human  race  will 
one  day  reap  the  full  harvest. 

In  the  preface  to  the  third  edition  of  The  Science  of  Nutrition, 
Professor  Graham  Lusk  said  in  1917:  "In  another  decade  the 
development  of  scientific  knowledge  will  probably  permit  the 
formulation  of  the  subject  from  the  standpoint  of  physical  chem- 
istry. It  cannot  now  be  so  treated."  It  seems  to  the  author  that 
a  few  years  must  elapse,  during  which  the  structural  changes  in 
the  protoplasm  of  the  different  tissues  which  result  from  specific 
faults  in  the  diet  are  accurately  described,  before  the  methods 
of  physical  chemistry  and  the  chemistry  of  colloidal  substances 

vii 


viii  PREFACE 

can  be  most  effectively  applied  to  the  problems  of  physiology. 
Recent  researches  on  the  anatomic  changes  seen  in  beri-beri, 
rickets,  scurvy  and  ophthalmia  of  dietary  origin,  represent  the 
beginning  of  the  task  of  preparing  the  field  for  the  physical 
chemist.  It  is  perhaps  not  too  optimistic  to  hope  that  the  next 
six  years  may  see  the  fulfillment  of  Professor  Lusk's  prophecy. 

It  seems  certain  that  a  new  era  in  nutrition  investigations  is 
at  hand.  Hitherto  this  branch  of  science  has  been  the  monopoly 
of  the  physiological  chemist.  He  must  now  share  his  heritage 
with  the  histologist  and  the  pathologist,  and  the  three  must  work 
together.  The  chemist  cannot  progress  far  toward  interpreting 
the  nature  of  the  changes  which  take  place  when  the  diet  is 
faulty  in  any  specific  sense.  He  can  interpret  now,  the  exact 
nature  of  the  dietary  error  which  has  produced  in  his  experi- 
mental animal  a  pathological  state,  but  with  existing  methods 
of  analysis  he  cannot  discover  what  part  of  the  structures  of  the 
protoplasm  have  been  injured.  He  can  see  loss  of  function 
but  cannot  explain  its  mechanism.  He  cannot  tell  what  changes 
have  taken  place  within  the  cells  of  special  tissues  as  the  result 
of  his  deliberate  disturbance  of  their  nutrition. 

The  science  of  pathology  now  suddenly  has  revealed  to  it  an 
opportunity  in  a  broad  field  of  great  practical  importance,  which 
it  has  never  before  enjoyed,  viz.:  an  opportunity  to  investigate 
morbid  anatomy  and  changes  of  function  with  a  background  of 
chemical  explanation  as  to  etiology. 

In  the  vast  literature  which  has  grown  up  within  a  few  years, 
relating  to  nutrition  investigations,  there  is  much  that  is  con- 
fusing to  one  who  would  undertake  to  familiarize  himself  with 
it.  Faulty  technic,  unwarranted  deductions,  premature  conclu- 
sions, and  conflicting  data  were  inevitable  in  investigations  in- 
volving so  many  variables  and  unknown  factors.  It  seemed  to 
the  author  that  there  is  great  need  of  a  careful  and  critical  inter- 
pretation of  the  existing  data  relating  to  nutrition,  in  order  that 
the  science  may  appear  in  its  proper  perspective.  It  was  with 
this  objective  that  the  present  volume  was  written.  In  order 
that  the  subject  might  be  clarified  it  was  necessary  that  elements 
of  weakness  in  a  considerable  amount  of  experimental  data  should 
be  pointed  out. 

The  ultimate  aim  of  scientific  investigations  is  to  give  man 
control  over  the  forces  of  Nature.  The  science  of  nutrition  gives 
promise  of  making  possible  the  realization  of  the  optimal  con- 
dition of  physical  well-being,  with  all  that  this  implies  for  the 
mental  achievement,  freedom  from  physical  defects  including 


PREFACE  ix 

tooth  decay,  and  immunity  to  many  of  the  ills  which  result  from 
invasion  of  the  tissues  through  breeches  in  the  barriers  of  bodily 
defense,  especially  through  decayed  teeth  and  a  debilitated  ali- 
mentary tract. 

The  author  has,  during  recent  years,  devoted  much  study  to 
the  dietary  habits  of  peoples  in  different  parts  of  the  world 
with  a  view  to  correlating  the  results  of  animal  experimentation 
with  those  of  human  experience  in  the  use  of  different  types  of 
diets.  The  results  of  this  study  are  presented  in  this  volume. 
It  is  believed  that  these  two  lines  of  investigation,  discussed  as 
they  are  in  their  relation  to  each  other,  point  unmistakably  to 
a  dietary  regimen  which  will  when  adopted  bring  about  marked 
improvement  of  the  human  race. 

It  is  a  privilege  to  acknowledge  the  services  rendered  by  Dr. 
V.  E.  Levine,  who  carefully  read  the  manuscript  during  its  prep- 
aration and  made  many  helpful  suggestions  for  its  improvement, 
and  by  Dr.  P.  G.  Shipley,  who  also  read  the  manuscript  and 
assisted  in  the  preparation  of  the  chapter  on  rickets.  Special 
appreciation  is  due  Miss  Nina  Simmonds  for  her  constant  in- 
terest and  criticism,  and  for  assistance  in  the  preparation  of  the 
bibliography  and  the  index.  Her  familiarity  with  the  extensive 
literature  of  nutrition  and  the  critical  sense  with  which  she  has 
examined  it,  contributed  in  no  small  degree  to  give  the  book 
such  value  as  it  may  possess. 

E.  V.  McCoLLUM 

Laboratory  of  Chemical  Hygiene 
School  of  Hygiene  and  Public  Health, 
Johns  Hopkins  University, 
Baltimore,  Md. 


TABLE  OF  CONTENTS 

CHAPTER 

I.  THE  BEGINNING  OF  A  NEW  ERA  IN  NUTRITION  STUDIES. 

The  method  of  study  of  nutrition  problems — The  prin- 
cipal components  of  protoplasm — The  study  of  food-stuffs 
by  chemical  method — Advances  in  our  knowledge  of  diges- 
tion— Failure  of  early  students  of  nutrition  to  profit  by  human 
experience — An  experiment  which  stimulated  investigations 
along  new  lines — Experiments  with  cattle  using  rations  derived 
from  a  single  plant  source — Vitality  of  young  depends  on  the 
character  of  the  diet  of  the  pregnant  mother— A  new  method 
of  investigation  was  necessary  if  further  progress  was  to  be 
made — The  problem  of  the  importance  of  organic  forms  of 
phosphorus— A  mistaken  conclusion  which  stimulated  research 
in  a  new  direction — A  new  opportunity  to  study  proteins  by  a 
biological  method — Vitamins  present  in  foods  supposed  to  be 
purified  1 

II.  A  BIOLOGICAL  METHOD  FOR  THE  ANALYSIS  OF  A  FOOD-STUFF. 

McCollum's  experiments  not  verified  by  Osborne  and  Men- 
del— Protein-free  milk  seemed  the  solution  of  the  problem  of 
studying  the  comparative  value  of  purified  proteins — Funk 
popularizes  the  "deficiency"  diseases — Osborne  and  Mendel's 
results  led  McCollum  to  study  further  the  cause  of  failure  of 
nutrition  with  purified  food  mixtures — Observations  on  the 
capacity  of  the  body  to  synthesize  the  complex  lipins — Dis- 
covery of  the  unique  properties  of  certain  fats  in  nutrition — 
Stepp's  experiments — Artificial  protein-free  milk — How  confu- 
sion regarding  essential  nutritive  factors  was  finally  cleared 
up — Studies  with  diets  restricted  as  to  source — The  biological 
method  for  the  analysis  of  a  food-stuff — Basis  of  differences 
in  nutritive  values  of  proteins — Demonstration  of  the  necessity 
of  two  vitamins  in  the  nutrition  of  the  rat — McCollum  and 
Davis  formulate  an  hypothesis  regarding  the  essentials  of  an 
adequate  diet — Usefulness  of  the  biological  method  for  the 
analysis  of  a  food-stuff 15 

III.  EARLIER  VIEWS  ON  NUTRITION  PROBLEMS. 

Beaumont's  views  on  digestion — Lavoisier's  studies  placed 
nutrition  on  a  scientific  basis — The  work  of  Pettenkofer  and 
Voit — Studies  on  protein  and  energy  in  nutrition — The  chem- 
ical method  of  food  analysis  and  the  data  it  yields — Propor- 
tions among  the  mineral  elements  in  food  was  long  regarded 
as  of  little  significance — Digestion  studies— Studies  of  sup- 
plementary values  of  foods — Conception  of  specific  effects 
of  nutrients — Efforts  to  study  food  requirements  by  statis- 
tical methods — A  mistaken  idea  regarding  economy  in  the 
purchase  of  foods — Chittenden's  idea  of  physiological  economy 
in  nutrition — Critchton-Browne's  views  on  parcimony  in  nu- 

xi 


xii  TABLE  OF  CONTENTS 

CHAPTER  PAGE 

tritipn— Effects  of  faulty  diets  on  life  history  of  animals- 
Optimal  better  than  "normal"  as  a  goal  in  planning  the  diet  .         40 

IV.  THE  NUTRITIVE  VALUE  OF  THE  PROTEINS  FROM  VARIOUS  SOURCES. 

Protein  the  most  prominent  organic  component  of  the  body — 
Nature  of  the  protein  molecule — Objectives  of  studies  relat- 
ing to  protein  in  nutrition — Power  of  the  tissues  to  synthesize 
proteins  from  amino-acids— Experiments  with  gelatin— Will- 
cock  and  Hopkins'  experiments  with  zein — Studies  of  Folin 
and  of  Van  Slyke — Nutritional  requirements  in  repair  versus 
growth — Studies  on  capacity  of  animal  to  utilize  ammonia 
as  a  source  of  protein — Comparative  nutritive  value  of  in- 
dividual proteins — Osborae  and  Mendel's  studies  of  protein 
metabolism — Properties  of  protein-free  milk — The  role  of 
lysine  in  nutrition— Can  the  mammary  gland  synthesize  ly- 
sine? — Is  lysine  the  limiting  factor  in  determining  the  value 
of  certain  proteins? — The  residual  nitrogen  of  protein-free 
milk — Lactalbumen  an  incomplete  protein — Mistaken  views 
as  to  the  unique  importance  of  lysine — A  method  for  the  com- 
parison of  the  values  of  individual  proteins 58 

V.  PECULIARITIES    OF    COMPOSITION    OF    PROTEINS    FROM    VARIOUS 

SOURCES. 

Certain  amino-acids  indispensable  in  nutrition — Elementary 
composition  of  the  proteins — Data  secured  by  the  Hausmann 
method  of  analysis — Data  secured  by  the  Van  Slyke  method 
— Data  secured  by  the  Kossel  method — Conditions  necessary 
for  the  comparison  of  proteins  by  feeding  experiments — In- 
dividual variation  in  rate  of  growth  in  rats — Conditions 
under  which  energy  and  protein  are  utilized  most  economically 
by  growing  animals— The  method  of  McCollum,  Simmonds 
and  Parsons  for  comparing  proteins — Importance  of  quan- 
titative data  regarding  food  consumption  by  experimental 
animals — Changing  food  consumption  with  growth — Appetite 
as  a  factor  in  food  consumption — Supplementary  values  of 
proteins  from  different  sources — Some  proteins  of  extraordinary 
value — Interpretation  of  value  of  a  diet — High  protein  con- 
sumption is  best 91 

VI.  THE  DIETARY  PROPERTIES  OF  INDIVIDUAL  FOOD-STUFFS. 

Results  obtained  with  the  biological  method  for  the  anal- 
ysis of  a  food-stuff — Wheat — Wheat  germ — Bolted  wheat 
flour — The  maize  kernel — Vitamin  content  of  different  sam- 
ples of  the  same  food  varies  considerably — Fat-soluble  A  con- 
tent of  yellow  vs.  other  colors  of  maize — Oats — Rice — Barley 
and  rye — Peas  and  beans — Soy  beans — Osborne  and  Mendel's 
studies  on  legume  proteins — Peanut — Cottonseed  products 
— The  leafy  parts  of  plants — Classification  of  foods  on  the 
basis  of  their  biological  function — Tubers — Fleshy  roots — 
Variation  in  fat-soluble  A  content  of  roots  with  yellow  and 
other  colors — Fruits — Citrous  fruits — Banana — Animal  tissues 
— Osborne  and  Mendel's  studies  of  vitamin  content  of  animal 
tissues — Muscle  meats  differ  greatly  from  glandular  organs 
in  dietary  properties — Animal  fats — Dietary  habits  of  carniv- 
orous animals  and  man — Milk — Fats  of  milk  as  a  source  of 
fat-soluble  A— Sour  milk— Eggs— Sea  foods 123 


TABLE  OF  CONTENTS  xiii 

CHAPTER  PAGE 

VII.  THE  VEGETARIAN  DIET. 

Vegetarianism  generally  practised  as  a  fad — Food  faddists 
frequently  discredit  themselves  by  their  philosophy — Meat 
eating  cannot  be  condemned  as  deadening  the  moral  faculties 
— The  more  valid  arguments  against  meat  eating — Slonaker's 
study  of  the  vegetarian  diet — Even  with  wide  variety  vege- 
tarianism is  likely  to  lead  to  disaster — Rats  can  be  grown 
successfully  on  a  strictly  vegetarian  diet — The  cause  of  the 
failure  of  Slonaker's  vegetarian  rats-— Evvard's  studies  on 
the  appetite  as  a  guide  to  the  selection  of  food — The  defi- 
ciencies in  inorganic  elements  in  seeds  are  quantitative  rather 
than  qualitative — Vegetarianism  has  been  viewed  from  the 
wrong  angle — Some  characteristics  of  vegetarian  diets — Cer- 
tain mineral  elements  are  essential  for  the  normal  function- 
ing of  the  tissues — Most  foods  are  too  poor  in  the  element 
calcium 157 

VIII.  THE  DIETARY  DEFICIENCY  DISEASES.    SCURVY. 

Relation  of  diet  to  certain  diseases  has  long  been  suspected 
— Symptoms  of  scurvy — Lime  juice  occasionally  proved  dis- 
appointing as  an  antiscorbutic  food — Many  lost  faith  in  the 
efficiency  of  lime  juice  as  an  antiscorbutic  food — Scurvy  at- 
tributed to  acidity  of  the  diet — The  classic  experiments  of 
Hoist  on  the  etiology  of  scurvy — McCollum  and  Pitz  drew 
faulty  deductions  from  their  experiments  on  scurvy — The  ear- 
lier views  of  Hess  and  Unger  on  the  cause  of  scurvy — Milk 
not  a  very  effective  antiscorbutic  food — The  rat  and  certain 
other  species  are  immune  to  scurvy — Cohen  and  Mendel's 
studies  on  scurvy — The  anatomical  lesions  in  scurvy — The  anti- 
scorbutic value  of  some  common  food-stuffs — The  effect  of 
heat  on  the  antiscorbutic  value  of  cabbage — Young  carrots 
are  better  than  old  as  antiscorbutic  food — Effect  of  drying 
on  the  antiscorbutic  potency  of  foods— Effect  of  aging  on 
the  antiscorbutic  substance — Tomato  withstands  heating  and 
retains  some  of  its  antiscorbutic  value — Citrous  fruits  and 
juices — Desiccated  fruits  and  vegetables  as  antiscorbutic 
foods — Rate  of  destruction  of  the  antiscorbutic  substance  dur- 
ing heating  of  cabbage — Antiscorbutic  value  of  canned  foods 
— Antiscorbutic  value  of  some  Indian  dried  foods — Antiscorbutic 
value  of  concentrated  fruit  juices— Effect  of  ultraviolet  light 
on  the  antiscorbutic  substance — No  antiscorbutic  value  to 
lean  beef — Raw  potato  a  good  antiscorbutic  food — Relation  of 
the  food  of  the  cow  to  antiscorbutic  value  of  the  milk — Anti- 
scorbutic value  of  dried  milks — The  diet  of  the  nursing 
mother — Relation  of  the  system  of  feeding  to  incidence  of 
scurvy  in  infants— Scurvy  in  infants  a  relatively  new  disease 
—Relation  of  pasteurization  of  milk  to  incidence  of  infantile 
scurvy 173 

IX.  THE  DIETARY   DEFICIENCY   DISEASES    (Continued).    BERI-BERI 

AND  POLYNEURITIS. 

The  antiquity  of  beri-beri — Symptoms  of  beri-beri — Theories 
as  to  its  etiology — Kanehiro's  studies  on  beri-beri  in  man — 
The  classic  experiment  of  Eijkman  in  the  production  of  ex- 
perimental beri-beri — Germ  of  rice  kernel  richest  part  in  con- 
tent of  anti-beri-beri  substance — Other  views  relating  to  the 


xiv  TABLE  OF  CONTENTS 

CHAPTER  PAGE 

cause  of  beri-beri — Sir  Patrick  Manson's  conclusions — Arsenic 
suggested  as  the  agent  causing  beri-beri — Fletcher's  studies 
on  human  beri-beri — Many  grades  of  injury  less  severe  than 
the  clinically  recognizable  deficiency  diseases — Schaumann's 
investigations — "Activator"  of  Schaumann — "Oryzanin"  of 
Suzuki — The  " fermentation  diseases"  of  Kohlbrugge — "Vita- 
mine"  of  Funk — Discovery  of  vitamins  did  not  lead  to  an 
understanding  of  diet — Two  forms  of  beri-beri — Epidemic 
dropsy,  war  edema  and  wet  beri-beri — Experimental  production 
of  edema  through  protein  starvation — Sequence  of  events  as 
famine  conditions  approach — Relation  between  wet  and  dry 
beri-beri — Two  or  more  deficiency  diseases  frequently  occur 
together — Comparison  of  diets  which  produce  beri-beri  or 
scurvy  with  those  which  induce  pellagra — Appleton's  observa- 
tions on  the  diet  in  Labrador  and  Newfoundland — Dietary 
deficiency  diseases  rarely  occur  uncomplicated — Prevention 
of  deficiency  diseases  does  not  necessarily  insure  good  nutri- 
tion— Borderline  malnutrition  causing  no  alarm  are  of  greater 
aggregate  importance  than  the  deficiency  diseases  ....  199 

X.  CHEMICAL  NATURE  OF  THE  ANTI-NEURITIC  SUBSTANCE,  WATER- 

SOLUBLE  B. 

Schaumann's  views  of  the  nature  of  the  anti-beri-beri  sub- 
stance—Funk's studies  on  the  isolation  of  "vitamine" — Other 
suggestions  as  to  the  nature  of  the  anti-beri-beri  substance — 
Williams'  investigations  on  hydroxy  pyridines — Activation  of 
adenine — Seidell's  silver  "vitamine"  compound — Myers  and 
Voegtlin's  procedure— Harden  and  Zilva's  results — Tethelin — 
McCarrison's  investigations  on  beri-beri — Nerve  lesions  less 
severe  than  those  seen  in  other  tissues— Subminimal  provi- 
sion of  vitamins  and  certain  diseases  of  children — McCarrison's 
view  of  the  relation  of  nuclear  nutrition  to  deficiency  dis- 
eases— Relation  of  appetite  to  intake  of  water-soluble  B — 
Beri-beri  does  not  appear  in  fasting  birds — Dutcher's  studies 
on  catalase — Findlay's  studies  on  glyoxalase  content  of  the 
tissues  in  normal  and  polyneuritic  birds — The  pigeon  test 
for  the  antineuritic  substance  of  no  value — The  test  employed 
by  McCollum  and  Simmonds — Attempts  to  employ  yeast  as 
a  test  organism  for  the  antineuritic  substance — Conclusions  .  221 

XI.  XEROPHTHALMIA  (KERATOMALACIA). 

The  necessity  of  a  fat-borne  vitamin  in  the  diet — Stepp's 
classic  experiments  with  lipin-free  diets — Comparison  of  birds 
with  mammals  with  respect  to  capacity  to  synthesize  com- 
plex lipins — Element  of  growth  not  included  in  Stepp's  ex- 
periments— Drummond's  view  that  fat-soluble  A  is  not  neces- 
sary for  maintenance  in  the  adult — The  experiments  of  Mc- 
Arthur  and  Luckett — Symptoms  resulting  from  specific  starva- 
tion for  fat-soluble  A — Hopkins'  experiments  showing  neces- 
sity of  "accessory"  food  substances — Osborne  and  Mendel 
described  ophthalmia  in  the  rat — McCollum  and  Simmonds 
prove  that  xerophthalmia  is  a  specific  deficiency  disease — 
Mori  described  ophthalmia  of  dietary  origin  in  Japanese 
children  as  early  as  1904 — Bloch's  cases  in  Denmark — Ophthal- 
mia in  infants  frequently  complicated  with  scurvy  or  other 
deficiency  disease — Hess  and  linger  express  the  view  that  fat- 


TABLE  OF  CONTENTS  xv 

CHAPTER  PAQB 

soluble  A  is  of  little  importance  in  human  nutrition — Urinary 
calculi  in  relation  to  deficiency  of  fat-soluble  A — Hemeralopia 
and  nyctalopia  possibly  associated  with  vitamin  deficiency  .  242 

XII.  CHEMICAL  STUDIES  OF  THE  DIETARY  ESSENTIAL,  FAT-SOLUBLE  A 

Best  sources  of  fat-soluble  A — Distribution  of  fat-soluble 
A  in  vegetable  foods— Yellow  maize  contains  more  fat-soluble 
A  than  other  varieties — Certain  leaves  are  very  rich  in  fat- 
soluble  A — Drummond  suggests  that  fat-soluble  A  is  one  of 
the  plant  yellow  pigments — Stevenson's  observations  on  caro- 
tin— Chickens  reared  on  diets  free  from  yellow  pigment — 
Palmer  and  Kennedy's  disproof  of  relation  of  fat-soluble  A 
to  yellow  pigments— Stability  of  fat-soluble  A  toward  heat— 
Fat-soluble  A  easily  destroyed  by  oxidation — Extraction  of 
fat-soluble  A  from  vegetable  tissues  by  means  of  solvents — 
Fat-soluble  A  not  destroyed  by  saponifying  agents — Methods 
of  estimating  fat-soluble  A  in  natural  foods— Pathological 
changes  resulting  from  lack  of  fat-soluble  A 258 

XIII.  THE  RELATION  OF  PELLAGRA  TO  DIET. 

Early  history  of  pellagra— Pellagra  symptoms— Theories  as 
to  the  cause — Goldberger's  studies  on  the  relation  of  the  diet 
to  pellagra — The  investigations  of  the  Robert  M.  Thompson 
commission,  and  the  Thompson  MacFadden  commission — 
The  studies  of  Jobling  and  Peterson  on  pellagra  in  Nash- 
ville—The eradication  of  pellagra  from  institutions  by  modi- 
fication of  the  diet — An  attempt  to  produce  pellagra  experi- 
mentally in  man  by  faulty  diet — Attempts  to  produce  the 
syndrome  of  pellagra  in  animals — Attempts  to  transmit  pel- 
lagra to  healthy  subjects— Voegtlin's  treatment  9f  pellagra 
with  vitamin  preparations — Voegtlin's  results  indicate  vita- 
min deficiency — Occurrence  of  pellagra  in  nursing  infants- 
Report  of  cases  of  pellagrous  mothers  nursing  babies  who  did 
not  develop  the  disease— Vedder's  interpretation  of  existing 
data  relating  to  the  cause  of  pellagra — Pellagra  can  be  pre- 
vented by  a  satisfactory  dietary  regimen 273 

XIV.  THE  RELATION  OF  THE  DIET  TO  •'SHE  ETIOLOGY  OF  RICKETS 

AND  RELATED  CONDITIONS. 

The  prevalence  of  rickets  in  children — The  characteristics 
of  the  disease — A  historical  survey  of  rickets — Geographical 
distribution  of  rickets — Rickets  absent  from  certain  parts  of 
the  Hebrides — Views  concerning  the  cause  of  rickets — Rickets 
does  not  occur  in  wild  animals — Relation  of  breast  feeding  to 
incidence  of  rickets— Some  regard  diet,  others  hygiene  as  the 
main  factor  in  inducing  rickets — Mellanby  suggests  that  rickets 
is  due  to  lack  of  fat-soluble  A — A  comparison  of  a  rachitic  and 
a  non-rachitic  dietary — Hess  and  Unger's  experiments  on  in- 
fants with  fat-poor  diets — Exercise  as  a  factor  in  preventing 
rickets  in  pups — Sequence  of  events  in  the  growth  of  bone — 
Abnormal  histological  changes  in  rachitic  bones — Recent  in- 
vestigations on  the  cause  of  rickets — Three  factors  operate 
in  the  etiology  of  rickets — The  ratio  between  calcium  and 
phosphorus  in  the  diet  is  very  important — Sherman  and 
Pappenheimer's  observation  on  rickets — Excessive  calcium 
content  in  the  diet  may  play  a  role  in  bone  pathology — Dis- 


xvi  TABLE  OF  CONTENTS 


cussion  of  Sherman  and  Pappenheimer's  experiments — Ratios 
between  calcium  and  phosphorus  more  important  than  their 
absolute  amounts — Protective  action  of  the  organic  factor 
concerned  in  the  causation  of  rickets — Further  observations  on 
changing  the  ratios  between  calcium  and  phosphorus  in  the 
diet — Rickets  is  essentially  a  disease  of  dietary  origin — The 
calcium  and  phosphorus  content  of  the  blood  in  health  and 
in  rickets — Why  is  rickets  common  in  some  places  and  rare 
in  others — Suggestion  of  cause  of  occurrence  of  rickets  in 
dogs  but  not  in  cats — Why  the  Eskimos  and  Lapps  are  free 
from  rickets— Rickets  rare  in  Iceland— The  teeth  in  rickety 
children — Primitive  man  had  neither  rickets  nor  decayed  teeth 
— Prevalence  of  decayed  teeth  among  American  children — 
Significance  of  the  absence  of  rickets  in  the  west  of  Ireland — 
Significance  of  the  conditions  in  the  Island  of  Lewis,  in  in- 
terpreting the  cause  of  rickets—A  method  for  demonstrating 
the  antirachitic  effect  of  cod  liver  oil — A  period  of  fasting 
may  initiate  the  healing  of  the  lesion  of  rickets — Parallelism 
between  increase  in  incidence  of  rickets  and  of  decayed  teeth  294 

XV.  THE  NURSING  MOTHER  AS  A  FACTOR  OF  SAFETY  IN  THE  NUTRI- 

TION OF  THE  SUCKLING. 

New  born  young  dependent  on  milk — Effect  of  faulty  diet 
on  the  capacity  of  the  lactating  female  to  produce  normal 
milk — Mammary  gland  has  no  power  to  synthesize  a  vita- 
min— Tendency  for  the  lactating  mother  to  sacrifice  her  tis- 
sues to  maintain  the  normal  composition  of  her  milk — Chem- 
ical composition  of  the  milk  of  pellagrous  women — The  effects 
of  under-feeding  on  the  lactating  cow  and  the  composition 
of  her  milk — Deficiency  in  the  milk  of  women  suffering  from 
beri-beri — A  cereal  diet  is  not  satisfactory  for  the  formation 
of  normal  milk — Failure  of  the  lactating  rat  to  induce  growth  in 
her  young  while  confined  to  a  diet  of  rolled  oats — Effect  on  the 
quality  of  the  milk  of  supplementing  the  oat  kernel — Inorganic 
content  of  the  diet  is  very  important  for  the  secretion  of 
normal  milk — The  nursing  mother  as  a  factor  of  safety  for 
her  young — Deficiencies  of  all  the  cereals  are  comparable  as 
material  for  the  elaboration  of  milk — Importance  of  the  "pro- 
tective foods"  in  the  nutrition  of  the  nursing  mother — Effect 
of  the  feed  of  the  cow  on  the  antiscorbutic  properties  of  her 
milk — Illustrations  of  the  gravity  of  various  types  of  faulty 
diets  on  quality  of  milk — Quality  of  milk  falls  off  before 
amount  of  secretion  is  markedly  interfered  with — Breast  milk 
not  a  satisfactory  food  unless  the  diet  of  the  mother  is  good — 
Rickets  may  occur  in  breast-fed  infants  when  mother's  diet  is 
faulty  in  certain  ways — All  who  escape  recognizable  nutri- 
tional disease  are  not  well  nourished — The  problem  of  pre- 
ventive dentistry  largely  one  of  feeding  during  infancy  and 
childhood 333 

XVI.  NEW  VIEWPOINTS  RELATING  TO  PRACTICAL  PROBLEMS  OF  NU- 

TRITION. 

The  importance  of  animal  experimentation  to  human  wel- 
fare— Nutrition  has  assumed  greater  importance  than  ever 
before — Many  are  still  unable  to  grasp  the  fundamentals  of 
scientific  nutrition — There  is  need  of  popularizing  the  new 


TABLE  OF  CONTENTS  xvii 


knowledge  of  nutrition — Entire  subject  must  be  viewed  from 
a  new  angle — Types  of  experimental  observations  which  made 
nutrition  a  new  science — The  experiments  of  Hopkins — Diffi- 
culties of  solution  of  the  fundamental  problems  of  nutrition 
— The  method  of  interpretation  of  McCollum  and  Davis — 
It  was  a  piece  of  good  fortune  that  the  earliest  experimental 
studies  were  made  with  the  rat — An  adequate  diet  may  be  re- 
markably simple — Great  stimulus  to  new  investigation  during 
the  last  few  years — Vegetable  foods  having  similar  biological 
functions  have  likewise  similar  dietary  properties — Early 
nutrition  investigators  ignored  human  experience  with  diets 
of  different  types — Scientific  nutrition  of  greater  value  in 
preventive  medicine  than  in  cure  of  disease — An  effort  to 
duplicate  human  experience  with  diet  with  a  rat  colony — 
Important  to  secure  effects  of  diet  on  life  history — Impossible 
to  state  the  minimum  requirement  of  any  one  food  factor  un- 
less all  dietary  factors  are  evaluated — Remarkably  accurate 
estimations  of  nutritive  value  are  possible  by  animal  experi- 
ments— A  specific  illustration  of  the  effects  of  faulty  nutrition 
— Effects  of  the  diet  in  determining  the  span  of  life — Fertility 
and  infant  mortality  are  valuable  indexes  to  the  state  of  nu- 
tritive well-being — One  may  have  a  surprising  variety  of  food 
and  still  have  a  faulty  diet — Any  diet  which  is  unsuited  for 
the  promotion  of  growth  in  the  young  will  not  be  satisfactory 
for  the  maintenance  of  health  in  the  adult — Effects  of  faulty 
nutrition  on  the  reaction  of  the  mother  toward  her  young 
— A  poorly  nourished  population  tends  to  be  the  product  of 
individuals  young  in  years — The  poorly  nourished  individual 
tends  to  hurry  through  his  span  of  life — A  striking  parallel 
between  human  experience  and  the  history  of  our  animals 
on  similar  diets — Nervousness  of  animals  on  certain  types  of 
faulty  diets — Tetanic  seizures  in  young,  nursing  mothers  whose 
diets  are  faulty  in  certain  ways — Infanticidal  tendencies  in 
nursing  mothers  caused  by  faulty  diet — Changes  in  our  basis 
of  judgment  regarding  criteria  of  quality  in  diet — The  diet 
should  be  as  near  the  optimum  as  possible  with  respect  to 
every  factor — Optimal  physical  development  and  the  preven- 
tion of  illness  the  present  day  objective — Possibilities  of 
scientific  nutrition  not  generally  appreciated 358 

^XVII.    THE  DIETARY  HABITS  OF  MAN  IN  SEVERAL  PARTS  OF  THE 
WORLD. 

The  polyphemic  eye  of  the  faddist  in  diet — The  keynote 
to  successful  nutrition  is  the  proper  selection  of  food — Ob- 
servations which  became  the  basis  of  important  deductions 
— Many  instances  of  successful  carnivorous  nutrition — Other 
tissues  make  good  the  deficiencies  of  muscle  tissue  in  carniv- 
orous feeding — Several  examples  of  a  successful  carnivorous 
nutrition  in  man — Lesson  from  the  health  experience  of  the 
non-citizen  Indians — Has  natural  vigor  anything  to  do  with 
susceptibility  to  tuberculosis? — The  food  of  the  Lapps— Atti- 
tude of  the  carnivora  toward  physical  activity — Metchnikoff's 
views  regarding  the  generation  of  toxic  products  in  the  intes- 
tine from  putrefaction  of  protein  food — Meat  eating  in  America 
is  very  different  from  practices  of  the  carnivora — The  teeth 
of  the  carnivora  were  excellent — The  nutrition  of  the  people 


xviii  TABLE  OF  CONTENTS 

CHAPTER  PAGE 

of  Iceland — The  diet  of  the  inhabitants  of  the  Hebrides — No 
rickets  among  the  children  of  the  Island  of  Lewis  in  the 
Hebrides — Good  nutrition  goes  far  toward  offsetting  the  effects 
of  bad  hygienic  surroundings — The  Oriental  diet — There  are  no 
strictly  vegetarian  peoples  in  the  sense  that  animals  are — 
The  importance  of  certain  articles  in  the  Oriental  diet — No 
food  in  China  and  other  Oriental  countries  suitable  for  feed- 
ing young  children — Difficult  to  maintain  normal  nutrition  in 
the  child  after  weaning —  Heredity  versus  nutrition  as  factors 
determining  the  size  of  a  people — The  climate  of  California 
not  so  stimulating  as  that  of  Japan — Importance  of  milk  in 
the  diet  of  western  nations  and  of  pastoral  peoples — The 
vigor  of  pastoral  nomads — The  Arabs  as  an  example  of  excel- 
lent nutrition — The  diet  of  the  pastoral  Arab — High  protein 
diet  is  excellent  if  properly  selected — McKay's  observations  on 
the  diet  and  physical  efficiency  of  Hindu  peoples— Relation  of 
the  consumption  of  dairy  products  to  health  in  parts  of 
Europe — Huntington's  views  on  the  effects  of  climate  on  man 
— Contrast  of  the  achievement  of  the  people  of  Canada  and 
those  of  the  Bermudas — Most  people  are  unwell — Plant  and 
animal  enemies  in  the  tropics  are  more  serious  than  climate — 
Under  what  conditions  does  man  tend  to  develop  best  intel- 
lectually— Of  all  factors  diet  is  the  most  important  in  deter- 
mining how  one  feels — Bad  health  conditions  in  the  United 
States  notwithstanding  its  stimulating  climate — The  cereal 
grains  as  a  menace  to  health — Changes  in  the  character  of  the 
American  diet  during  recent  decades — Evidences  that  we  have 
exceeded  the  limits  of  safety  in  the  consumption  of  cereals — 
More  about  the  dietary  habits  of  early  man — Domestic  animals 
made  possible  the  utilization  of  grass  for  conversion  into  hu- 
man food — Changes  in  the  diet  during  the  great  industrial 
era — lodin  as  a  limiting  factor  in  human  and  animal  nu- 
trition in  certain  regions — The  struggle  in  Agriculture  be- 
tween meat  production  and  dairying 386 

"XVIII.    THE  MOST  FUNDAMENTAL  PROBLEM  IN  PREVENTIVE  DEN- 
TISTRY. 

Recognition  of  the  need  of  strengthening  the  social  fabric 
— The  importance  of  physical  well-being — Evidence  of  phys- 
ical deterioration — The  bottle  feeding  of  infants — Some  new 
and  unfavorable  influences  are  at  work  to  undermine  health — 
Some  observations  on  American  School  Children — More  can 
be  achieved  through  dietary  reform  than  through  any  other 
agency — The  story  of  Adam — Prenatal  life,  infancy,  and  early 
childhood  are  the  critical  periods — Malnutrition  is  usually 
the  primary  cause  of  physical  inferiority  in  childhood — 
The  basis  of  preventive  dentistry  is  satisfactory  nutrition 
during  development — The  prevailing  ideas  regarding  preventive 
dentistry  are  based  on  wrong  premises — The  most  satisfactory 
type  of  diet — Mistaken  view  regarding  the  cause  of  the  phys- 
ical excellence  of  primitive  peoples — Concluding  statement  .  436 


THE  NEWER  KNOWLEDGE 
OF  NUTRITION 


THE  NEWER  KNOWLEDGE 
OF  NUTRITION 


CHAPTER  I 

THE  BEGINNING  OF  A  NEW  ERA  IN  NUTRITION 

STUDIES 

i.    The   Method   of   Study   of    Nutrition   Problems. — Our 

knowledge  of  nutrition  has  progressed  hand  in  hand  with  the  de- 
velopment of  the  science  of  Chemistry.  Chemical  science  has 
given  us  the  clue  to  an  understanding  of  the  nature  of  the  food- 
stuffs and  the  changes  which  take  place  in  digestion,  as  well  as 
an  appreciation  of  some  of  the  secrets  of  the  metabolic  processes 
which  take  place  within  the  tissues  of  the  body.  Chemistry  will 
continue  as  time  goes  on  to  aid  in  extending  our  knowledge  of  the 
finer  processes  of  physiology.  Nevertheless,  it  has  been  possible 
for  a  time  to  advance  more  rapidly  in  the  study  of  nutrition,  from 
the  theoretical  as  well  as  from  the  practical  standpoint,  by  a 
systematic  feeding  of  simplified  diets  to  animals,  than  by  means 
of  chemical  studies.  The  results  are  interpreted  on  the  observa- 
tions as  to  the  ability  or  inability  of  the  animals  to  develop  as  the 
diets  are  modified.  Progress  has  resulted  in  the  past,  and  will 
continue  in  the  future  to  come  from  the  judicious  division  of  labor 
between  the  study  of  food  problems  by  chemical  methods  and  by 
animal  experimentation.  In  this  brief  exposition  of  the  present 
situation  respecting  our  knowledge  of  foods  and  nutrition  it  is  de- 
sired to  present  to  the  reader  an  appreciation  of  the  viewpoint  of 
an  investigator.  It  will  be  possible  in  this  way  to  convey  to  him 
an  appreciation  of  the  line  of  reasoning  by  which  the  successive 
steps  in  the  progress  of  the  last  few  years  have  been  attained.  A 
brief  historical  account  of  the  researches  in  this  field  will  serve 
this  purpose.  It  will,  at  the  same  time,  illustrate  the  mental  proc- 
esses of  the  students  engaged  in  bringing  order  into  this  field  of 
scientific  inquiry,  where  before  there  was  no  clear  understanding. 
2.  The  Principal  Components  of  Protoplasm. — A  plant 
structure  or  an  animal  body  is  an  exceedingly  complex  system  of 

1 


2         THE  NEWER  KNOWLEDGE  OF  NUTRITION 

chemical  substances,  many  of  which  are  themselves  individually 
as  complex  in  their  structure  as  the  most  complicated  machine. 
The  first  step  in  the  direction  of  reaching  an  understanding  of  the 
chemistry  of  the  living  tissues  must  involve  the  separation  and 
study  of  the  structural  units  of  which  they  are  composed.  This 
was,  indeed,  the  field  of  activity  of  many  organic  and  biological 
chemists  during  the  nineteenth  century.  The  fats  and  the  sim- 
pler substances  into  which  they  can  be  converted  in  the  process 
of  saponification  were  the  subjects  of  exhaustive  studies.  The 
complex  carbohydrates  and  the  simpler  sugars  were  discovered, 
and  the  manner  in  which  they  are  related  chemically  was  made 
clear.  The  most  complex  of  the  food  substances,  the  proteins, 
were  by  far  the  most  difficult  to  study  by  chemical  means.  Famil- 
iar examples  of  these  are  egg  white,  the  casein  of  milk,  and  the 
principal  components  of  meat.  Certain  proteins  which  occur  in 
our  plant  and  animal  foodstuffs  differ  very  greatly  in  their  physi- 
cal properties,  but  they  are  nevertheless  very  closely  related 
chemically,  since  they  can  all  be  resolved  into  the  same  digestion 
products.  These  have  been  studied  with  marked  success  as  to 
their  behavior  with  the  digestive  juices  produced  in  the  pancreas 
or  alimentary  tract  and  with  chemical  reagents  in  the  laboratory. 
In  addition  to  these  prominent  components  of  plant  and  animal 
structures,  a  long  list  of  relatively  simple  chemical  substances 
have  been  discovered  and  isolated  in  a  state  of  purity  from  vege- 
table and  animal  tissues.  They  have  been  investigated  to  deter- 
mine their  composition  and  special  properties,  and  tests  by  means 
of  which  they  can  be  recognized  and  identified  and  methods  for 
their  quantitative  estimation  in  certain  cases  have  been  worked 
out. 

Through  a  century  of  patient  labor  by  many  able  men  we  came 
to  an- appreciation  of  the  number  and  character  of  the  simple 
structural  units  into  which  the  tissues  of  an  animal  or  a  plant 
can  be  separated.  Furthermore,  certain  of  these  simple  bodies 
could  be  recognized  as  intermediate  products  in  the  course  of  the 
building  up  of  more  highly  organized  complexes;  certain  others 
were  shown  to  be  degradation  products  resulting  from  the  physi- 
ological activity  of  the  living  tissues.  Through  these  studies  it 
became  established  that  the._liody  of  an  animal  or  the  tissues  of 
a  plant  consist  essentially  of  proteins,  carbohydrates,  fats,  and 
a  series  of  related  substances  which  are  collectively  Joiqwn  as 
lipins.  The  proteins  are  rich  in  the  element  nitrcgenTthe  average 
content  of  this  element  being  not  far  from  16  per  cent. 
Several  other  prominent  components  of  the  living  tissue  contain 


THE  BEGINNING  OF  A  NEW  ERA  3 

more  or  less  of  this  element,  so  that  this  is  not  an  essential 
characteristic.  With  these  substances  there  are  always  asso- 
ciated  in  the  living  tissues  more  or  less  water  and  a  number  of 
inorganic  elements  in  molecular  or  ionic  form.  A  number  of 
special  kinds  of  each  of  the  types  of  substances  enumerated 
above  became  known,  and  their  less  obvious  characteristics  were 
described.  Certain  substances  were  found  to  be  special  products 
elaborated  only  by  certain  tissues  and  under  definite  conditions. 
These  became  regarded  from  the  standpoint  of  nutrition  as  of 
subordinate  interest.  Examples  of  these  are  the  alkaloids, 
quinin,  strychnin,  and  cellulose.  This  last  one  serves  as  skeletal 
tissues  for  the  plant  but  is  not  essential  for  the  animal.  In  the 
same  category  belong  the  waste  products  of  the  life  processes  of 
the  animal  body,  such  as  urea,  uric  acid  and  creatinin,  most  of 
which  are  not  found  in  plant  tissues. 

Living  structures  on  analysis,  although  always  associated  with 
numerous  substances,  the  exact  importance  of  which  could  not  in 
many  cases  be  determined,  were  found  to  consist  essentially  of 
proteins,  carbohydrates,  fats,  mineral  salts  and  water.  These 
came  to  be  regarded  even  as  early  as  1840  as  the  essential  and 
never  failing  components  of  plant  tissues,  and  were  looked  upon 
as  the  fundamental  factors  in  the  diet  of  animals. 

3.  The  Study  of  Foodstuffs  by  Chemical  Methods,— It  be- 
came very  early  the  principal  activity  of  investigators  in  nu- 
trition to  discover  and  perfect  methods  for  the  analysis  of  food- 
stuffs, in  order  to  determine  the  amounts  of  protein,  carbohy- 
drate, fat  and  ash  contained  in  them.  There  were  observed 
pronounced  differences  in  the  composition  of  the  many  sub- 
stances which  serve  as  food  for  man  and  animal.  Meats,  milk, 
eggs  and  a  few  seeds,  such  as  the  pea  and  bean,  are  very  rich  in 
protein.  The  cereal  grains  contain  much  less  of  this  foodstuff, 
and  the  fruits,  tubers  and  vegetables,  especially  in  the  fresh 
condition,  contain  very  little.  Equally  great  variations  are  ob- 
servable in  the  water  content  of  foods,  and  in  their  yields  of 
fats  and  carbohydrates.  One  of  the  great  epochs  in  the  develop- 
ment of  the  science  of  nutrition  is  that  in  which  Atwater  and 
his  associates  in  America,  and  Voit  in  Germany,  examined  and 
tabulated  in  classified  form  the  chemical  composition  of  an 
extensive  list  of  human  foods  (1).  Following  this,  Agricultural 
Experiment  Stations  accumulated  similar  data  concerning  sub- 
stances used  for  feeding  animals.  Previous  to  1900  the  idea 
that  there  was  any  marked  variation  in  the  quality  of  proteins 


4         THE  NEWER  KNOWLEDGE  OF  NUTRITION 

from  different  sources  did  not  become   generally   appreciated. 

It  seems  remarkable,  in  the  light  of  the  revelations  in  the  field 
of  nutrition  during  the  last  few  years,  that  close  students  of 
nutrition  accepted  for  so  long,  and  without  experimental  proof, 
the  belief  that  the  results  of  a  chemical  analysis  revealed  the 
dietary  values  of  foodstuffs. 

4.  Advances  in  Our  Knowledge  of  Digestion, — The  proc- 
esses of  digestion  of  food  are  so  remarkable  that  they  have  been 
made  the  subject  of  extensive  study  by  many  of  the  ablest  stu-  / 
dents  of  physiology  and  biochemistry.  The  chemistry  of  the  * 
fats  and  carbohydrates  is  somewhat  simpler  than  that  of  the 
proteins,  and  their  structure  and  transformations  came  to  be 
earlier  understood.  It  was  not  until  the  close  of  the  nineteenth 
century  that  the  nature  and  extent  of  protein  digestion  became 
fully  appreciated.  Soon  after  1900  the  researches  of  Kossel  and 
of  Fischer  revealed  the  great  variation  in  the  composition  of 
proteins  from  different  sources  (2).  This  discovery  introduced 
into  nutrition  studies  the  idea  of  quality  of  protein  in  addition 
to  quantity.  A  statement  of  the  quantity  of  protein  had  hitherto 
seemed  satisfactory  to  students  of  nutrition.  Most  proteins  were 
found  to  be  resolvable  into  seventeen  or  eighteen  simple  diges- 
tion products  called  amino-acids,  and  it  was  observed  that  the 
proportions  in  which  these  were  present  in  the  protein  molecule 
varied  greatly  in  the  proteins  from  different  sources.  All  or 
nearly  all  of  these  digestion  products  appear  to  be  indispensable 
components  of  an  adequate  diet.  The  extensive  and  valuable 
researches  of  Osborne  have  shown  that  all  natural  foods  contain 
several  proteins  (3) .  Although  there  are  individual  proteins,  such 
as  gelatin  and  zein  (from  maize),  which  are  entirely  lacking  in 
one  or  more  of  the  essential  digestion  products,  every  natural 
food  appears  to  contain  more  or  less  of  each  of  them.  The  pro- 
tein mixture,  which  is  found  in  any  natural  food,  such  as  the 
grains,  tubers,  meats,  etc.,  may  be  regarded  as  biologically  com- 
plete, but  their  biological  values  differ  greatly,  depending  on  the 
yield  of  the  several  amino-acids  obtained  from  them. 

This  appreciation  of  the  differences  in  biological  values  of 
proteins  from  different  sources  represented  an  awakening  from  a 
state  of  tranquillity  among  physiologists,  who  had  come  to  be- 
lieve, about  the  year  nineteen  hundred,  that  chemistry  had  re- 
vealed all  the  more  important  facts  relating  to  foods  and  nutri- 
tion. As  we  look  back  now  upon  the  recorded  observations  which 
had  been  made  from  time  to  time  for  centuries,  especially  by 


THE  BEGINNING  OF  A  NEW  ERA  5 

those  whose  viewpoint  was  essentially  that  of  the  pathologist,  it 
is  difficult  to  see  how  all  the  able  students  of  nutrition  during  the 
nineteenth  century  should  have  so  completely  ignored  their  find- 
ings which  pointed  to  a  close  relation  between  the  diet  and 
disease. 

5.  Students  of  Nutrition  Failed  to  Profit  by  Human  Ex- 
perience.— In  several  parts  of  the  world  restricted  diets  of  a 
monotonous  character  have  for  centuries  produced  diseases  in 
man.  The  only  one  of  these  which  was  at  all  common  in  the 
Western  hemisphere  wasj3curyy.  This  disease  caused  much  suf- 
fering among  sailors  in  the  days  of  the  long  voyages  before  the 
advent  of  steam  navigation.  It  was  well  understood  from  the 
early  part  of  the  eighteenth  century  that  scurvy  was  the  result 
of  the  consumption  of  a  faulty  diet  composed  usually  of  biscuits 
and  salt  meats.  It  was  also  known  that  prompt  recovery  re- 
sulted from  the  consumption  of  liberal  amounts  of  fresh  fruits 
and  vegetables.  Decades  passed  without  any  systematic  attempt 
being  made  to  determine  the  cause  of  the  peculiar  value  of  this 
class  of  foods. 

pellagra  has  been  a  scourge  among  the  poorest  peasants  in 
some  parts  of  Italy  and  France  for  centuries,  and  its  etiology  has 
been  referred  by  many  to  the  poor  quality  of  the  simple  and 
monotonous  diet.  This  disease  was  not  observed  in  America 
until  after  1900.  After  that  time  it  increased  rapidly  up  to  1917, 
especially  in  the  Southern  States. 

Beri-beri  is  a  disease  common  among  the  poorest  classes  of 
the  Orient,  who  limit  their  food  supply  principally  to  polished 
rice  and  fish.  It  is  remarkable  that  not  until  the  year  1897 
was  the  first  fertile  suggestion  made  as  to  the  nature  of  the 
dietary  fault  which  was  responsible  for  the  development  of  this 
disease.  This  observation  was  made  by  the  Dutch  physician, 
Eijkman. 

Man  has  been  sufficiently  industrious  in  most  parts  of  the 
world  to  secure  for  himself  a  varied  diet,  which  he  derives  from 
the  cereal  grains  and  legumes,  fruits,  roots,  tubers,  meats  and 
certain  edible  leaves.  Beginning  with  the  dawn  of  the  era  of  his 
most  rapid  advance  toward  achievement,  he  has  in  many  parts 
of  the  world  been  the  possessor  and  protector  of  flocks  and  herds, 
which  provided  him  with  clothing  and  a  constant  supply  of  meat 
and  milk.  The  importance  of  this  last  item  in  his  food  supply 
we  have  but  recently  come  to  appreciate.  The  famous  chemist, 
Van  Helmont,  called  milk  "brute's  food,"  and  thought  it  advis- 


6         THE  NEWER  KNOWLEDGE  OF  NUTRITION 

able  to  substitute  for  it  bread  boiled  in  beer  and  honey.  Baron 
Liebig  likewise  thought  of  preparing  a  substitute  for  milk  in 
his  "Food  for  Infants."  In  later  chapters  of  this  book  it  will  be 
made  clear  how  tragic  it  is  for  the  health  of  an  infant  to  attempt 
to  replace  the  most  important  single  human  food  by  some  mix- 
ture made  up  on  the  basis  of  chemical  composition  in  imitation 
of  human  milk.  It  is  with  a  view  to  establishing  an  apprecia- 
tion of  the  great  differences  in  the  nutritive  value  of  foods  the 
composition  of  which  is  such  as  to  make  them  appear  alike  from 
the  results  of  chemical  analysis,  that  the  present  account  of  the 
progress  attained  by  the  investigations  of  recent  years  was 
prepared. 

6.  An  Experiment  which  Stimulated  Investigations  along 
New  Lines. — In  1906  an  experiment  was  begun  at  the  Wisconsin 
Experiment  Station  which  had  a  far-reaching  effect  on  the  minds 
of  students  of  nutrition.  It  was  planned  by  S.  M.  Babcock,  and 
was  carried  out  by  Hart  and  Humphrey,  with  the  later  co-opera- 
tion of  Steenbock  and  the  author.  In  this  experiment  the  object 
was  to  determine  whether  rations  for  cattle  so  made  up  as  to  be 
alike  insofar  as  could  be  determined  by  chemical  analysis,  but 
derived  each  from  a  single  plant,  would  prove  to  be  of  equal 
nutritive  value  for  growth  and  the  maintenance  of  vigor  (4) . 

The  ration  employed  for  one  group  of  animals  was  derived 
solely  from  the  wheat  plant,  and  consisted  of  wheat  straw,  wheat 
gluten  and  the  entire  wheat  grain.  The  ration  of  a  second  group 
consisted  of  the  entire  corn  plant,  which  included  the  kernel, 
stalk,  and  the  leaf,  together  with  a  portion  of  corn  gluten,  a  by- 
product of  the  cornstarch  industry.  The  third  group  obtained 
their  ration  solely  from  the  oat  plant,  being  fed  entirely  on 
rolled  oats  and  oat  straw  and  leaf.  There  was  a  fourth  group, 
which  it  was  supposed  would  serve  as  controls,  that  was  fed  a 
ration  having  the  same  chemical  composition,  but  derived  from 
about  equal  portions  of  wheat,  corn  and  oat  products. 

The  animals  employed  were  young  heifer  calves  weighing  about 
350  pounds,  and  were  as  nearly  comparable  in  size  and  vigor  as 
could  be  secured.  They  were  restricted  absolutely  to  the  ex- 
perimental ration.  They  were  given  all  the  salt  (NaCl)  they 
cared  to  eat,  were  well  cared  for,  and  were  allowed  to  exercise 
in  an  open  lot  free  from  vegetation.  Their  behavior  during 
growth  and  during  the  performance  of  the  functions  of  reproduc- 
tion were  extremely  interesting.  All  groups  ate  practically  the 
same  amounts  of  feed  and  digestion  tests  snowed  that  there  were 
no  differences  in  the  digestibility  of  the  three  rations. 


THE  BEGINNING  OF  A  NEW  ERA  7 

7.  The  Corn  Plant  a  Better  Ration  for  Cattle  Than  the 
Wheat  or  Oat  Plants. — It  was  not  until  the  animals  had  been 
confined  to  the  experimental  rations  for  a  year  or  more  that 
differentiation  in  their  appearance  was  easily  observable.    The 
corn-fed  group  was  sleek  and  fine,  and  evidently  in  an  excellent 
state  of  nutrition.     In  marked  contrast  stood  the  wheat-fed 
group.    These  animals  were  rough  coated  and  gaunt  in  appear- 
ance, and  small  of  girth  as  compared  with  those  fed  the  corn- 
plant  ration.    The  weights  of  the  two  groups  did  not  differ  in  a 
significant  degree.    The  groups  fed  the  oat-plant  ration  and  the 
mixture  of  the  three  plants,  leaf  and  seed,  stood  intermediate 
between  the  lots  just  described.    The  assumption  that  the  ani- 
mals receiving  the  mixture  of  products  would  fare  better  than 
the  others,  and  thus  serve  as  the  standard  group  for  controls, 
did  not  prove  correct.    The  corn-fed  animals  were  at  all  times 
in  a  better  state  of  nutrition  than  were  those  receiving  the  greater 
variety  of  food  materials. 

8.  Vitality  of  Young  Depends  on  the  Character  of  the  Diet 
of  the  Pregnant  Mother. — The  reproduction  records  of  these 
animals  are  of  special  interest.    The  corn- fed  heifers  invariably 
carried  their  young  to  full  term.    The  young  showed  remarkable 
vigor,  and  were  normal  in  size  and  able  to  stand  and  suck  within 
an  hour  after  birth,  as  is  the  rule  with  vigorous  calves.    All  lived 
and  developed  in  a  normal  manner.    The  young  of  the  wheat- 
fed  mothers  were  the  reverse  in  all  respects.     They  were  born 
three  to  four  weeks  too  soon,  and  were  small,  weighing  on  an 
average  46  pounds,  whereas  the  young  of  the  corn-fed  animals 
weighed  73  to  75  pounds  each.    The  latter  weight  is  normal  for 
new-born  calves.     The  young  of  the  wheat-fed  mothers  were 
either  dead  when  born  or  died  within  a  few  hours.    The  young 
of  the  mothers  which  had  grown  up  on  the  oat-plant  ration  were 
almost  as  large  as  those  from  the  corn- fed  mothers,  the  average 
weight  being  71  pounds.    All  of  the  cows  in  this  group  produced 
their  young  about  two  weeks  too  soon.     One  of  the  four  was 
born  dead,  two  were  very  weak  and  died  within  a  day  or  two 
after  birth.     The  fourth  was  weak  but  with  care  it  was  kept 
alive.    The  young  of  the  cows  which  were  fed  the  mixture  of 
the  three-plant  products  were  weak  in  most  cases.    One  was 
born  dead  and  one  lived  but  six  days.    The  mothers  were  con- 
tinued on  the  experimental  rations  and  the  following  year  they 
repeated  in  all  essential  details  the  reproduction  records  ob- 
served in  the  first  gestation  periods. 

9.  Milk  Production  as  an  Index  to  Vitality. — Records  were 


8         THE  NEWER  KNOWLEDGE  OF  NUTRITION 

kept  of  the  milk  production  during  the  first  thirty  days  of  the 
first  lactation  period.  The  average  production  per  day  per  each 
individual  of  the  corn-fed  lot  was  24.03  pounds;  for  the  wheat- 
fed  animals  8.04,  and  for  the  oat-fed  animals  19.38  pounds. 
Those  fed  the  mixture  of  the  three  plants  produced  an  average 
of  19.82  pounds  of  milk  per  cow  per  day  during  the  first  thirty 
days.  In  the  second  lactation  period  the  average  figures  for 
milk  production  were  28.0,  16.1,  30.1  and  21.3  pounds,  respec- 
tively, per  day  during  the  first  thirty  days. 

Through  autopsy  and  analysis  of  the  tissues  of  the  young, 
and  analysis  of  the  feeds  and  excreta  of  the  animals  of  the 
several  groups,  an  elaborate  attempt  was  made  to  solve  the 
problem  of  the  cause  of  the  marked  differentiation  of  the  animals 
fed  these  restricted  diets.  Interesting  data  were  secured  which 
showed  marked  differences  in  the  character  of  the  fat  in  the 
milk  of  the  cows  of  the  different  lots.  The  observation  was 
made  that  the  urine  of  the  wheat-fed  animals  was  invariably 
distinctly  acid  in  reaction,  whereas  that  of  the  other  lots  was 
alkaline  or  neutral.  It  was  not  possible  by  any  means  known 
to  biological  chemistry  to  work  out  a  reason  as  to  the  cause  of 
the  pronounced  differences  in  the  physiological  well-being  of 
the  different  lots  of  cows. 

10.  A  New  Method  of  Investigation  Was  Necessary  if  Fur- 
ther Progress  Was  to  Be  Made. — This  experiment  confirmed 
the  author's  conviction  that  the  only  way  in  which  the  problems 
of  nutrition  could  ever  be  solved  was  to  work  out  the  problem 
of  the  success|uLiee.ding.of  the  most  simplified  diets  possible. 
If  this  were  accomplished  it  would  be  possible  to  proceed  from 
the  simplest  diet  to  the  complex  diets  employed  in  practical 
nutrition.  It  would  also  be  possible  to  ascertain  the  nature  of 
the  dietary  faults  in  each  of  the  natural  foods,  singly,  the  seed 
alone  and  the  leaf  alone,  before  attempting  to  interpret  the 
cause  of  malnutrition  in  animals  fed  the  more  complex  mixtures. 

Several  investigators  had  already  made  efforts  to  nourish 
young  laboratory  animals  on  mixtures  of  purified  protein,  starch, 
sugar,  fats  and  mineral  salts,  but  in  all  cases  without  success. 
Steinitz  (5),  Leipziger  (6),  Zadik  (7),  Ehrlich  (8),  Socin  (9), 
Hall  (10),FaltaandN6ggerath  (11),  Jacob  (12),Marcuse  (13), 
Henrique  and  Hansen  (14),  and  Willcock  and  Hopkins  (15),  had 
all  employed  such  food  mixtures.  In  all  these  trials  directed 
toward  the  nutrition  of  animals  with  food  mixtures  which  con- 
tained everything  considered  in  the  ordinary  food  analysis,  the 


THE  BEGINNING  OF  A  NEW  ERA  9 

animals  lost  weight  steadily  from  the  beginning  of  the  experi- 
ments. They  died  unless  the  diet  was  changed.  It  was  im- 
possible at  the  time  to  explain  the  reason  for  their  failure. 

11.  Nutrition  Studies  Must  Be  Conducted  with  Small  Ani- 
mals.— Studies  of  this  character  must  of  necessity  be  carried 
out  with  small  laboratory  animals,  because  it  is  difficult  and 
laborious  to  prepare  the  purified  foodstuffs  in  sufficient  amounts 
for  the  conduct  of  feeding  experiments.     It  is,  however,  highly 
desirable  to  shorten  the  length  of  such  experiments  as  far  as 
possible  by  the  employment  of  sjiort-liveclomnivorous  animals 
which  grow  rapidly  and  which  quickly  reach  maturity.    In  this 
way  it  is  possible  to  accumulate  data  sufficiently  fast  to  make 
progress  reasonably  satisfactory.    The  domestic  rat  serves  this 
purpose  admirably.    It  has  a  gestation  period  of  but  21  days 
and,  under  normal  conditions,  the  young  are  ready  to  wean  at 
the  age  of  25  days.    The  female,  when  well  nourished,  usually 
produces  her  first  litter  at  the  age  of  90  days,  and  will,  if  properly 
handled,  have  five  or  more  litters  by  the  time  she  reaches  an  age 
of  fourteen  months,  which  age  ordinarily  marks  the  end  of  her 
period  of  fertility.    The  extreme  span  of  life  of  the  well-fed  rat 
is  about  thirty-six  months.     By  using  such   an   animal   it  is 
possible  to  accomplish  within  a  relatively  short  time  the  accumu- 
lation of  data  regarding  growth  and  reproduction  which  it  would 
take  years  to  secure  with  domestic  animals  of  large  size,  long 
period  of  gestation  and  long  span  of  life.    With  the  latter  the 
expense  would  be  prohibitive.    In  1907  the  author  took  up  the 
study  of  the  cause  of  the  failure  of  animals  to  grow  on  mixtures 
of  purified  foodstuffs  and  employed  the  domestic  rat  as  the 
experimental  animal. 

12.  The  Problem  of  the  Importance  of  Organic  Forms  of 
Phosphorus. — As  can  be  seen  by  the  titles  of  several  of  the  papers 
cited  in  connection  with  the  feeding  of  isolated  and  purified  food 
substances,  one  of  the  earliest  explanations  which  occurred  to 
investigators  as  the  possible  cause  for  the  failures  was  the  prob- 
able need  of  the  animal  for  phosphorus  in  certain  organic  com- 
binations.   Some  of  the  experiments  were  interpreted  as  support-  ••> 
ing  the  view  that  proteins  containing  phosphorus  as  a  part  of  , 
the  molecule  were  better  utilized  for  growth  than  were  phos- 
phorus-free proteins.    Between  1895  and  1910  there  was  a  wide- 
spread belief  among  students  of  this  subject  that  the  presence 
of  organically  bound  phosphorus  might  be  a  factor  of  great 
importance  in  nutrition.    It  is  easy  to  appreciate  how  this  idea 


10       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

gained  credence.  Casein,  the  principal  protein  of  milk,  is  a 
phosphorus-containing  protein,  and  the  yolk  of  egg  is  very  rich 
in  both  the  phosphorized  protein,  vitellin,  and  in  phosphorized 
fats.  Milk  and  the  egg  yolk  are  peculiarly  constituted  for  the 
role  they  play  in  reproduction  and  the  nutrition  of  the  young 
during  the  earliest  period  of  post-natal  life  when  growth  is  most 
rapid.  It  seems  significant  that  in  these  two  substances  organi- 
cally bound  phosphorus  is  very  abundant,  whereas  it  is  abundant 
nowhere  else  among  our  natural  foods.  It  has  never  been  con- 
clusively shown  up  to  the  present  time  that  a  protein  occurs  in 
plant  tissues  which  contains  the  element  phosphorus  as  a  part  of 
its  molecule.  Other  organic  phosphorus  compounds  (lecithins, 
nucleic  acids)  do  exist  in  plant  tissues  but  never  in  great 
abundance. 

Among  the  experiments  cited  above  in  which  animals  were 
confined  to  diets  of  purified  proteins,  carbohydrates,  fats  and 
mineral  salts,  those  of  Hall,  Steinitz,  Leipziger,  Zadik  and  Ehr- 
lich  were  directed  towards  ascertaining  the  importance  of  phos- 
phorus in  organic  as  contrasted  with  inorganic  combinations. 
Other  investigators  working  along  the  same  lines  were  Korn- 
auth  (16),  Gottstein  (17),  Ehrstrom  (18),  Hirschler  and  Ter- 
ray  (19),  Gilbert  and  Posternak  (20),  Tunnicliffe  (21),  LeClerc 
and  Cook  (22),  Koch  (23),  Hart,  McCollum  and  Fuller  (24), 
and  Forbes  (25) .  The  evidence  either  seemed  definitely  to  sup- 
port the  view  that  organic  phosphorus  compounds  were  essential 
in  the  diet  or  else  it  failed  to  establish  the  fact  that  they  were 
dispensable. 

13.  Inorganic  Phosphates  Suffice  for  All  Nutritive  Needs 
of  an  Animal. — In  1909  McCollum  (26)  introduced  a  new  feature 
into  experiments  of  this  type  by  seeking  to  increase  the  variety 
of  foodstuffs  in  the  diet  as  far  as  possible,  with  the  hope  of  ob- 
taining success  where  others  had  failed  to  secure  satisfactory  nu- 
trition in  animals.    In  the  series  of  experiments  referred  to  the 
one  condition  which  was  required  of  every  organic  component  of 
the  ration  was  that  it  should  be  free  from  phosphorus  in  any 
form.    This  condition  was  practically  met.    The  only  source  of 
phosphorus  in  the  diet  was  finely  ground  tricalcium  phosphate, 
a  natural  mineral. 

14.  A  Mistaken  Conclusion  Which  Stimulated  Research  in 
a  New  Direction. — This  paper  is  deserving  of  special  notice 
because  it  reported  the  first  successful  growth  experiments  with 
a  food  supply  which  was  at  that  time  considered  as  essentially 


THE  BEGINNING  OF  A  NEW  ERA  11 

a  mixture  of  purified  foodstuffs,  every  one  of  which  could  be 
named.  It  seemed  to  demonstrate  that  the  view,  which  had 
long  held  sway,  that  the  only  substances  necessary  in  the  diet 
are  proteins,  carbohydrates,  fats  and  certain  mineral  salts,  was 
indeed  well  founded.  It  appeared  to  prove  that  the  cause  of 
the  failure  of  the  earlier  experiments  of  this  type  was  due  to  the 
lack  of  palatability  of  the  food,  which  led  to  failure  of  the  ani- 
mals to  ingest  sufficient  quantities  of  food.  This  was  one  of 
the  conclusions  of  the  author,  but  it  has  since  become  apparent 
that  this  viewpoint  was  a  mistaken  one. 

The  proteins  employed  were  edestin  from  the  hemp  seed  and 
zein  from  maize.  Corn  starch,  wheat  starch,  milk  sugar,  glucose, 
cane  sugar,  butter  fat,  bacon  fat,  and  cholesterol,  a  substance 
found  in  most  body  tissues  and  having  physical  properties  simi- 
lar to  fats,  together  with  the  ash  constituents,  made  up  the  food 
supply.  No  effort  was  made  to  feed  a  constant  mixture.  On  the 
contrary,  the  diet  was  changed  from  day  to  day  as  far  as  pos- 
sible in  order  to  prevent  the  dreaded  loss  of  appetite.  On  this 
food  supply  several  young  rats  gained  in  weight,  one  somewhat 
more  than  doubling  its  weight  in  fifty-six  days.  These  results 
were  interpreted  as  meaning  that  growth  had  actually  been  in- 
duced by  a  mixture  of  purified  food  substances,  where  all  pre- 
vious attempts  had  failed.  The  only  difference  between  the  ex- 
perimental diet  used  in  this  study  and  those  of  the  earlier  in- 
vestigators appeared  to  be  in  the  palatability  factor.  Important 
deductions  were  drawn  from  these  results  concerning  certain 
synthetic  reactions  which  the  body  tissues  could  accomplish. 
Five  years  later  it  became  apparent  that  the  cause  of  the  growth 
of  this  group  of  animals  lay  in  the  chance  inclusion  in  the  diet 
of  milk  sugar,  which  was  not  as  pure  as  it  was  supposed  to  be, 
and  to  the  inclusion  of  butter  fat.  Each  of  these  we  now  know 
furnished  a  substance  indispensable  for  either  growth  or  main- 
tenance. But  a  surprisingly  small  amount  of  each  of  these  is 
necessary  in  order  to  induce  the  maintenance  and  the  growth 
secured  in  these  experiments. 

15.  A  New  Opportunity  to  Compare  the  Nutritive  Values 
of  Individual  Proteins. — On  the  publication  of  the  paper  in 
which  these  experimental  results  were  described  in  1909,  it  ap- 
peared to  be  established  that  the  long  accepted  views  concerning 
what  the  diet  must  contain  in  order  to  be  adequate,  were  correct, 
and  that  the  chemical  methods  for  the  analysis  of  foods  actually 
afforded  data  from  which  the  nutritive  properties  of  a  diet  could 


12       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

be  appraised.  The  data  also  seemed  effectually  to  dispose  of  the 
disputed  question  concerning  the  relative  merits  of  phosphorized 
as  compared  with  phosphorus- free  proteins,  and  indeed,  could 
be  interpreted  only  to  mean  that  the  animal  body  is  capable  of 
synthesizing  from  salts  of  inorganic  phosphoric  acid,  all  the 
complex  phosphorus-containing  organic  substances  which  are  so 
important  as  components  of  living  matter. 

These  ideas  being  accepted  as  proven  facts,  it  seemed  that  the 
next  great  advance  in  the  field  of  nutrition  investigations  was  in 
the  field  of  study  of  the  relative  values  of  the  numerous  proteins 
of  the  plant  and  animal  tissues,  which  organic  chemists  had  been 
recently  studying  by  improved  methods,  and  which  they  showed 
to  be  very  differently  constituted  when  derived  from  different 
sources.  The  chemical  methods  were  not  entirely  satisfactory 
for  the  analysis  of  these  complex  bodies.  Even  in  the  hands  of 
the  most  skilled  chemists,  among  whom  Kossel,  Fischer,  and 
Aberhalden  in  Germany  and  Osborne  in  America  were  the  most 
noted,  only  a  little  more  than  half  of  the  protein  molecule  could 
be  accounted  for  in  the  form  of  identifiable  products  of  diges- 
tion, the  amino-acids.  Obviously  such  analyses,  although  repre- 
senting a  marked  advance  in  chemical  science,  were  too  incom- 
plete to  permit  of  using  them  as  a  basis  of  judgment  as  to  the 
nutritive  values  of  individual  proteins.  The  way  now  seemed 
open,  however,  for  the  quantitative  comparison  of  individual  pro- 
teins, carefully  isolated  and  purified,  by  feeding  a  single  protein 
as  the  sole  source  of  this  dietary  factor,  and  with  a  diet  which 
was  otherwise  complete  and  satisfactory.  A  series  of  such  ex- 
periments in  which  proteins  from  various  sources  were  employed, 
should  reveal  differences  in  their  values  for  transformation  into 
body  proteins  during  growth.  The  experimental  studies  of  Mc- 
Collum,  just  discussed,  seemed  to  make  such  investigations  pos- 
sible. In  1909  Osborne  and  Mendel  undertook  to  carry  out  such 
a  series  of  researches  on  purified  proteins.  Osborne  had  for 
many  years  made  a  thorough  study  of  the  number  and  nature 
of  the  proteins  in  various  cereals,  legume  seeds,  nuts,  oil  seeds 
and  of  certain  animal  tissue  proteins,  and  possessed  the  knowl- 
edge, skill  and  equipment  for  their  preparation  on  a  large  scale. 

16.  Two  Vitamins  Were  Present  in  Foods  Supposed  to  Be 
Purified. — Unfortunately,  for  the  progress  of  this  branch  of 
physiological  chemistry,  the  diet  which  McCollum  had  employed 
successfully  for  the  promotion  of  growth  in  young  rats  was 
something  more  than  it  appeared  to  be.  It  was  not  actually  a 


THE  BEGINNING  OF  A  NEW  ERA  13 

simple  mixture  of  proteins,  several  carbohydrates,  fats  and  in- 
organic salts,  but  contained  as  impurities,  two  nutritive  princi- 
ples which  were  unsuspected.  One  of  these  was  in  the  milk 
sugar,  although  this  was  believed,  on  the  basis  of  careful  tests, 
to  be  highly  purified  lactose;  the  other  was  an  uncharacterized 
substance  which  the  butter  fat  contained.  The  failure  of  all  in- 
vestigators in  this  field  to  appreciate  this  led  to  confusion  for 
several  years.  The  further  history  of  investigations  which 
cleared  up  this  problem  will  be  given  in  the  following  chapter. 

BIBLIOGRAPHY 

1.  Voit,    von    C.:      Physiologie    des    Stoffwechsels,    1881.     Cited    from 

Lusk,  G.    Science  of  Nutrition,  3rd  Edition,  1917. 
Atwater,   W.   A.:     Chemical   Analysis   of   American   Food   Materials, 
Bull.  28,  United  States  Dept.  of  Agric. 

2.  Fischer,  E.:     Chemistry  of  the  Proteins.    Mann,  G.,  London,  1914. 

3.  Osborne,  T.  B.:    The  Vegetable  Proteins.     Monographs  on  Biochem- 

istry, Longmans,  Green  and  Company. 

4.  Hart,  E.  B.,  McCollum,  E.  V.,  Steenbock,  H.,  and  Humphrey,  G.  C.: 

Physiological  Effect  on  Growth  and  Reproduction  of  Rations  Bal- 
anced from  Restricted  Sources.  Wise.  Agric.  Expt.  Sta.,  Research 
Bull.  No.  17,  1911. 

5.  Steinitz,  F.:    Ueber  das  Verhalten  phosphorhaltiger  Eiweisskorper  im 

Stoffwechsel.    Pfliiger's  Archiv,  1898,  Ixxii,  75. 

6.  Leipziger,    R.:     Ueber    Stoffwechselversuche    mit    Edestin.     Pfliiger's 

Archiv,  1900,  Ixxviii,  402;  Also  Inaug.  Diss.,  Breslau,  1899. 

7.  Zadik,  H.:    Stoffwechselversuche  mit  phosphorhaltigen  und  phosphor- 

freien  Eiweisskorpern.    Pfluger's  Archiv,  1899,  Ixxvii,  1. 

8.  Ehrlich,  P.:     Stoffwechselversuche  mit  P-haltigen und P-freien Eiweiss- 

korpern.   Inaug.  Diss.,  Breslau,  1900. 

9.  Socin,  C.  A.:    In  welcher  Form  wird  das  Eisen  resorbirt?    Zeitschrift 

f.  Physiol.  Chemie,  1891,  xv,  93. 

10.  Hall,  W.  S.:     Ueber  das  Verhalten  des  Eisens  in  Thierischen  Organis- 

mus.    Du  Bois-Reymond's  Archiv  Physiol.  Abth.,  1896,  49. 

11.  Falta,  W.  und  Noggerath,  C.  T.:    Futterungsversuche  mit  kiinstliche 

Nahrung.    Hofmeister's  Beitrage,  1905,  vii,  313. 

12.  Jakob,  L.:     Futterungsversuche  mit  einer  aus  den  einfachen  Nahrungs- 

stoffen  zusammengesetzten  Nahrung  an  Tauben  und  Ratten.  Zeit. 
f.  Biol.,  1906,  xlix,  19;  Auch.  Diss.  Munich,  1906. 

13.  Marcuse,  G.:     Ueber  den  Nahrwerth  des  Caseins.     Pfluger's  Archiv, 

1896,  Ixiv,  223. 

14.  Henrique,    V.,    und    Hansen,    C.:    Ueber    Eiweissynthese   im    Thier- 

korper.    Zeit.  f.  Physiol.  Chem.,  1905,  xliii,  417. 

15.  Willcock,  E.,  and   Hopkins,   F.   G.:    The  Significance  of  Individual 

Amino-Acids  in  Metabolism.  The  Action  of  Tryptophane  with 
Zein  as  the  only  Source  of  Nitrogen.  Jour,  of  Physiol.,  1906,  xxxv,  88. 

16.  Kornauth,  K.:  Futterungsversuche  mit  einem  Hunde  bei  Verabreichung 

Verscheidener  stickstoffhaltiger  Materialien.  Zeit.  f.  d.  Landwirt- 
schaftliche  Versuchswesen  im  Oesterreich,  1900,  iii,  1;  133. 


14       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

17.  Gottstein,  E.:  Ueber  das  Verhalten  von  Calcium  und  Magnesium  im 

einigen  Stoffwechselversuchen  mit  phosphorhaltigen  und  phosphor- 
freien  Eiweisskorpern.    Inaug.  Diss.,  Breslau,  1901. 

18.  Ehrstohm,  R.:     Zur  Kenntniss  des  Phosphorumsatzes  bei  erwachsenen 

Menschen.  Skand.  Arch.  Physiol.,  1903,  xiv,  82. 

19.  Hirschler,  A.,  und  Terray,  P. :     Ueber  die  Bedeutung  der  anorganischen 

Salze  im  Stoffwechsel  des  menschlichen  und  thierischen  Organismus. 
Math.  u.  naturwiss.  Ber.  aus  Ungarn,  1905,  xx,  145. 

20.  Gilbert,  A.,  and  Posternak,  S.:     La  medication  phosphoree  envisagee 

au  point  de  vue  des  echanges  nutritifs  de  Porganisme.    L'CEuvre 
med.-chir.,  1903,  xxxvi,  48. 

21.  Tunnicliffe,  F.  W.:    The  Behavior  in  the  Body  of  Certain  Organic 

and  Inorganic  Phosphorus  Compounds.    Congres  Internal,  de  med., 
Lisbonne,  1906,  xv,  181-sect.  4. 

22.  Le   Clerc,   J.   A.,   and   Cook,   F.   C.:     Metabolism    experiments   with 

Organic  and  Inorganic  Phosphorus.    Jour.  Biol.  Chem.,  1906,  ii,  203. 

23.  Koch,  E.:     Ein  Beitrag  zum  Phosphorstoffwechsel.     St.  Petersburger 

med.  Wochenschr.,  1906,  xxxi,  400. 

24.  Hart,   E.   B.,   McCollum,   E.   V.,   and   Fuller,   J.   G.:    The   Role    of 

Inorganic   Phosphorus   in  the   Nutrition  of  Animals.    Amer.  Jour, 
of  Physiol.,  1909,  xxiii,  246. 

25.  Forbes,  E.  B.:    The  Metabolism  of  Organic  and  Inorganic  Phosphorus 

Compounds.    Ohio  Agric.  Exp.  Sta.    Bull.  No.  6,  1914.    (Discussion 
of  Literature.) 

26.  McCollum,  E.  V.:    Nuclein  Synthesis  in  the  Animal  Body.     Amer. 

Jour,  of  Physiol.,  1909,  xxv,  120. 


FIG.  1. — Photograph  of  a  cow  which  grew  up  on  a  ration  derived  solely  from 
the  corn  plant.  The  seed,  straw  and  leaf  of  the  plant  were  all  included  in  the 
food  mixture.  Her  nutrition  was  excellent,  as  shown  by  her  appearance,  the 
vigor  of  her  offspring  and  her  ability  to  produce  an  abundance  of  milk.  Figure 
2  shows  a  photograph  of  her  calf,  taken  soon  after  it  was  born.  Rations  con- 
sisting of  the  entire  plant  may  be  highly  satisfactory.  The  seed  of  the  plant 
is  never  in  itself  a  complete  food. 


FIG.  2. — Photograph  of  calf  produced  by  a  mother  whose  ration  had  been 
long  derived  from  the  corn  plant  as  the  sole  source  of  nutriment.  It  was  vigor- 
ous and  developed  normally.  The  entire  wheat  plant,  seed,  leaf  and  stem  make 
a  diet  which  can  support  growth,  but  not  good  nutrition.  The  corn  kernel 
alone  does  not  induce  growth. 


Fio.  4. — Calf  produced  by  cow  shown  in  Figure  3.  It  was  born  prematurely, 
weighed  but  little  more  than  half  as  much  as  calves  normally  do  at  birth,  and  was 
dead  when  born.  The  importance  of  the  source  of  the  food  supply,  both  for  the 
nutrition  of  mother  and  the  unborn  young,  is  strikingly  illustrated  by  these  animals. 
(Figures  1  to  4  are  from  Research  Bulletin  17  of  the  Wisconsin  Experiment  Station.) 


CHAPTER  II 

A  BIOLOGICAL  METHOD  FOR  THE  ANALYSIS  OF 
A  FOODSTUFF 

17.  McCollum's  Experiments  Not  Verified  by  Osborne  and 
Mendel. — It  was  pointed  out  in  the  preceding  chapter  that  re- 
peated failures  characterized  experimental  studies  in  which  ani- 
mals were  confined  to  diets  containing  only  the  well  established 
food  principles.  These  failures  had  practically  established  the 
belief  that  this  line  of  study  was  unprofitable,  because  all  ani- 
mals, for  some  unknown  reason,  died  when  confined  to  such  a 
regimen.  The  apparently  conclusive  results  of  McCollum  with 
such  mixtures  aroused  hope  that  a  new  and  valuable  body  of 
data  could  be  secured  which  would  reveal  the  sources  of  the 
valuable  and  less  valuable  proteins  among  our  natural  foods. 

In  1909  Osborne  and  Mendel  took  up  this  line  of  investigation 
and  proceeded  to  feed  individual  proteins  with  a  diet  which 
was  otherwise  composed  of  purified  starch,  lard  and  mineral 
salts.  At  the  outset  of  their  studies  they  accepted  the  evidence 
which  McCollum  had  presented  that  this  could  be  successfully 
done  and  planned  to  interpret  on  the  basis  of  the  capacity  of 
young  rats  to  grow  on  a  constant  diet,  varied  in  successive  ex- 
periments only  with  respect  to  its  protein,  the  relative  merits  of 
such  proteins  as  tissue  builders.  They  did  not,  however,  actually 
duplicate  the  experimental  conditions  of  McCollum,  but  adopted 
a  diet  which  they  regarded  as  having  essentially  the  same  prop- 
erties. This  consisted  of  purified  protein,  such  as  casein  of 
milk,  starch,  lard  and  a  salt  mixture.  They  met  with  complete 
failure  in  these  attempts  to  nourish  their  animals  with  such  a 
diet.  They  tried  a  salt  mixture  recommended  by  Rohmann  (1) 
with  which  he  had  met  with  success  with  a  diet  consisting  in 
great  measure  of  purified  food  substances,  and  also  the  salt  mix- 
ture described  by  McCollum.  In  all  cases,  however,  their  ani- 
mals declined  steadily  from  the  time  they  were  confined  to  such 
diets.  They  proceeded  a  step  farther  and  established  the  fact 
that  the  failure  of  the  animals  was  not  due  to  lack  of  appetite, 

15 


16       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

since  the  food  intake  was  found  to  be  sufficient  to  promote 
growth  provided  the  composition  of  the  food  had  been  satis- 
factory. At  that  time  no  one  was  able  to  see  any  important 
difference  between  the  quality  of  a  purified  protein,  three  carbo- 
hydrates, one  being  milk  sugar,  two  kinds  of  fats,  one  being  but- 
ter fat,  and  a  salt  mixture,  as  compared  with  a  simple  mixture 
of  protein,  starch,  lard  and  salts. 

1 8.  Osborne  and  Mendel  Prepare  "Protein-Free  Milk." — 
Following  their  failure  to  nourish  animals  satisfactorily  on  a 
diet  of  isolated  and  purified  foodstuffs,  Osborne  and  Mendel  (2) 
adopted  what  they  apparently  regarded  as  essentially  the  equiva- 
lent of  a  mixture  of  purified  food-stuffs.  The  basis  of  their 
new  diet  was  28  per  cent  of  "protein-free  milk,"  a  product  made 
by  removing  as  completely  as  possible  the  fat,  casein  and  lactal- 
bumen  from  milk,  and  evaporating  the  resulting  whey  to  dry- 
ness.  The  residue  was  a  yellow  solid,  easily  ground  to  a  powder, 
consisting  for  the  most  part  of  milk  sugar  and  the  mineral  salts 
originally  present  in  the  milk.  In  fact,  no  other  components  of 
the  product  could  be  named.  "Protein-free  milk"  was  found 
to  contain  about  0.7  per  cent  of  nitrogen,  but  the  form  in  which 
it  was  present  could  not  be  ascertained. 

They  prepared  diets,  using  28  per  cent  of  this  "protein-free 
milk,"  the  remainder  of  which  consisted  of  starch,  lard,  agar- 
agar,  and  the  protein  which  they  desired  to  study.  This  com- 
bination had  certain  properties  which  could  not  be  accurately 
defined,  but  which  made  it  far  superior  to  any  of  the  simple 
mixtures  used  by  others.  With  these  diets  they  were  able  with 
certain  proteins  to  secure  in  rats  normal  growth  to  the  full  adult 
size.  The  results,  judging  from  the  widespread  comments  on 
these  experiments,  were  regarded  by  many  as  the  final  triumph 
in  this  type  of  experimental  work. 

Since  Osborne  and  Mendel  considered  their  diet  containing 
"protein-free  milk"  as  suitable  for  the  purpose  which  they  had 
in  view,  the  comparison  of  the  relative  values  of  various  iso- 
lated proteins,  they  apparently  abandoned  further  efforts  to 
solve  the  problem  of  what  was  lacking  in  their  former  diets  of 
purified  food-stuffs.  They  did,  however,  prepare  an  "artificial 
protein-free  milk"  from  what  they  regarded  as  pure  milk  sugar 
and  a  mixture  of  mineral  salts  made  up  from  reagent  bottles, — 
an  attempt  being  made  to  imitate  exactly  the  composition  of 
the  "natural  protein-free  milk."  With  this  mixture  in  place  of 
the  natural  product  they  secured  excellent  growth  records  over 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS       17 

periods  covering  two  months  or  a  little  longer  (3).  They  made 
a  special  effort  to  secure  lactose  and  salts  of  a  high  degree  of 
purity  for  certain  of  their  experiments  in  which  "artificial  pro- 
tein-free milk"  was  used.  This  preparation  gave  negative  results 
in  most  cases,  and  in  all  the  amount  of  growth  was  decidedly  less 
than  when  materials  of  ordinary  purity  were  used.  They  car- 
ried their  investigations  in  this  direction  no  further  than  to  make 
the  addition  of  traces  of  iodin,  manganese,  fluorin  and  aluminum. 
These  additions,  the  "impurities"  suspected  in  their  reagents  of 
poorer  quality,  actually  improved  the  diet,  making  it  capable 
of  inducing  better  and  more  continuous  growth,  which,  however, 
ceased  before  growth  was  completed.  Osborne  and  Mendel  were 
for  a  time  inclined  to  accept  the  view  that  the  peculiar  virtue 
of  their  natural  "protein-free  milk"  lay  in  the  nice  adjustment 
of  the  inorganic  elements  and  radicals  it  contained. 

19.  Students  of  Nutrition  Had  Ignored  the  Observations 
of  Pathologists  on  Deficiency  Diseases. — With  this  understand- 
ing of  the  experience  and  views  of  the  various  investigators  of  the 
subject  of  nutrition,  it  is  of  interest  to  look  back  from  our  pres- 
ent position  and  point  out  the  problems  waiting  to  be  solved. 

There  had  been  in  the  literature  of  pathology  for  many  years 
abundant  evidences  from  human  experience  that  a  diet  may 
have  an  appropriate  chemical  composition  and  yet  be  unsatis- 
factory for  the  nutrition  of  man.  These  observations  did  not 
secure  from  students  of  nutrition  the  attention  they  merited.  It 
had  been  known  for  centuries  that  certain  diets  of  stale  foods 
produced  outbreaks  of  scurvy  among  sailors,  soldiers,  prisoners 
and  others,  and  that  fresh  vegetables  and  fruits  would  promptly 
relieve  the  trouble  if  they  were  taken  in  the  early  stages  of  the 
disease.  Nobody  had,  however,  even  in  the  first  decade  of  the 
twentieth  century,  made  an  effort  on  a  comprehensive  plan  to 
discover  what  it  was  in  certain  foods  which  caused  them  to  be 
incomplete  and  to  induce  disease,  and  what  it  was  in  certain 
other  foods  which  made  them  of  specific  therapeutic  value. 

Beri-beri,  a  peripheral  neuritis  resulting  in  paralysis,  had  been 
known  from  remote  times.  In  1884  it  was  demonstrated  beyond 
doubt  by  the  Japanese  Navy  that  it  was  due  to  faulty  diet.  Un- 
der the  direction  of  Admiral  Takaki  a  ship  made  a  cruise  of 
eight  months,  during  which  time  the  incidence  of  beri-beri  among 
the  sailors  was  carefully  noted.  Another  ship  was  then  manned 
and  sent  on  a  second  cruise  over  the  same  course,  but  with  an 
improved  dietary  furnished  the  men.  The  effects  were  so  strik- 


18       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

ing  that  the  diet  of  the  army  and  navy  was  remodelled  and  im- 
proved, with  the  result  that  thereafter  the  disease  practically  dis- 
appeared. In  1897  Eijkman,  a  Dutch  physician,  sought  to  test 
the  question  whether  there  was  any  relation  between  the  con- 
sumption of  polished  rice  and  the  incidence  of  beri-beri.  He 
found  that  pigeons  or  chickens  that  were  restricted  to  a  diet  of 
milled  rice  developed  in  two  to  four  weeks  a  condition  of  paral- 
ysis strikingly  suggestive  of  beri-beri  in  man.  He  established 
the  relation  between  milled  rice  and  the  disease,  and  showed  that 
there  was  something  in  the  bran  layer  which  protected  against  it. 
Although  several  pathologists  had  repeated  and  confirmed  this 
observation,  it  did  not  influence  students  of  nutrition  until  after 
Funk,  a  Polish  chemist,  called  attention  to  this  work  in  1910, 
when  he  designated  the  term  "vitamine"  to  indicate  a  group  of 
indispensable  nutritive  complexes  (4). 

20.  Funk  Popularizes  the  Deficiency  Diseases. — To  Funk 
is  due  the  credit  of  bringing  to  the  attention  of  all  the  view  that 
there  are  certain  diseases  which  result  from  faulty  diet,  the  fault 
consisting  in  a  lack,  relative  or  absolute,  of  one  or  another  of 
several  substances,  each  of  which  when  present  in  the  diet  pro- 
tects against  a  specific  type  of  breakdown  of  the  tissues.  Beri- 
beri, scurvy,  pellagra  and  rickets  were  all  attributed  by  him  to 
lack  of  "vitamines"  in  the  diet.  Actually  he  had  experimental 
evidence  of  the  existence  of  only  one  of  these  specific  "deficiency" 
diseases,  beri-beri  or  polyneuritis,  as  it  is  called  when  produced 
experimentally  in  animals.  This  was  the  only  one  of  the  syn- 
dromes enumerated  which  had  been  studied  experimentally  in  a 
manner  that  could  be  regarded  as  affording  a  basis  for  judgment 
as  to  their  etiology. 

Human  experience  had,  however,  been  practically  as  definite 
as  animal  experimentation  in  demonstrating  that  scurvy  could 
be  cured  with  certain  fresh  foods,  but  not  by  the  same  foods  in 
a  stale  condition.  As  will  be  pointed  out  later,  however,  there 
was  much  difference  of  opinion  as  to  the  cause  of  scurvy.  The 
vitamins  made  a  great  impression  on  the  public  mind  and  justly 
so.  There  is  nothing  more  spectacular  than  the  restoration  of  a 
pigeon  which  has  been  brought  to  a  condition  of  helplessness 
by  a  diet  of  polished  rice.  Within  a  few  hours  of  death  it  can 
be  brought  back  to  an  apparently  normal  condition  by  the  ad- 
ministration of  but  an  insignificant  amount  of  properly  prepared 
substance. 

Funk  had  no  clear  conception  of  the  importance  of  the  several 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        19 

factors  which  go  to  make  up  an  adequate  diet,  for  in  1910  he 
knew  how  to  produce  but  one  deficiency  disease,  polyneuritis 
or  beri-beri.  This  was  effected  in  the  same  manner  that  Eijk- 
man  had  done  it  in  1897,  by  restricting  animals  to  polished  rice 
as  their  sole  food  supply.  These  observations  in  pathology 
failed  at  that  time  to  impress  the  students  of  normal  nutrition. 
Rice  is  now  known  to  be  faulty  with  respect  to  four  dietary 
factors  for  the  rat,  and  with  respect  to  five  factors  for  man. 

21.  McCollum  Was  Led  by  Osborne  and  Mendel's  Results 
to  Study  Further  the  Purified  Food  Mixture. — It  has  been 
stated  already  that  Osborne  and  Mendel    (5)    reported  their 
failure  to  induce  growth  in  young  rats  on  a  diet  composed  of 
purified  casein,  starch,  lard  and  the  inorganic  salt  mixtures  em- 
ployed by  Rohmann  and  by  McCollum,  and  it  was  evident  from 
their  records  of  food  intake  that  sufficient  food  had  been  con- 
sumed to  promote  growth  if  the  quality  was  satisfactory. 

No  explanation  was  apparent  for  their  failure,  for  the  diet  of 
McCollum,  with  which  successful  growth  had  been  reported,  con- 
sisted of  two  pure  proteins,  several  carbohydrates,  including  milk 
sugar,  two  fats,  including  butter  fat,  and  a  salt  mixture  (see  p. 
11).  It  had  been  supposed  that  the  success  observed  with  this 
food  mixture  was  due  to  adequate  food  consumption.  An  effort 
was  at  once  begun  by  McCollum  to  discover  wherein  lay  the 
lack  of  harmony  in  these  observations.  As  the  situation  stood, 
his  work  was  discredited,  and  he  felt  that  many  would  be  in- 
clined to  regard  his  reported  data  as  falsified.  It  was  now 
imperative  that  he  should  satisfactorily  explain  why  others  had 
failed  to  confirm  his  results. 

Returning,  therefore,  to  this  field  of  study,  he  found  his  results 
irregular  and  confusing.  Employing  a  diet  consisting  of  casein, 
dextrinized  starch,  milk  sugar,  and  salts,  he  and  Miss  Davis 
tried  the  addition  of  a  series  of  different  kinds  of  fats,  to  see  if 
any  special  virtue  could  be  found  in  any  of  these,  and  in  1912-13, 
found  that  young  rats  restricted  to  such  a  diet  could  grow  well 
when  butter  fat  or  egg  yolk  fats  were  incorporated  in  this  food, 
but  that  olive  oil  or  lard  did  not  under  these  conditions  induce 
any  growth.  These  results  were  not  described  until  June,  1913. 
They  interpreted  these  results  to  mean  that  there  was  in  certain 
fats  a  dietary  essential  whicty  had  not  hitherto  been  recognized. 

22.  Investigations  on  the  Synthesis  of  Complex  Lipins  by 
the  Animal  Body. — McCollum  and  Davis  appreciated  the  fact 
that  the  animal  body  is  capable  of  producing  synthetically  the 


20       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

complex  lipins,  or  fat-like  substances  such  as  lecithin,  which  in 
addition  to  glycerol  and  fatty  acids  contains  phosphoric  acid 
and  a  nitrogenous  base  called  cholin.  McCollum,  Halpin  and 
Drescher  (6)  had  shown  that  young  hens  could  grow  for  a  con- 
siderable time  on  a  diet  free  from  this  class  of  substances,  and 
while  confined  to  it,  could  produce  many  eggs  in  which  were 
contained  much  more  of  the  complex  lipins  than  the  bodies  of  the 
hens  could  furnish,  they  remaining  in  good  health  at  the  end  of 
the  experiment.  Butter  fat  is  free  from  lecithin  and  related  sub- 
stances, so  their  data  led  McCollum  and  Davis  to  the  conclusion 
that  the  stimulating  effect  of  butter  fat  on  growth  could  not  be 
attributed  to  any  known  lipin. 

In  1912,  Osborne  and  Mendel  (7)  published  a  paper  describing 
successful  nutrition  over  a  considerable  period  of  time  with  diets 
which  contained  no  fats  and  but  traces  of  substances  soluble  in 
fat  solvents  such  as  ether.  This  paper  tended  greatly  to  con- 
fuse the  entire  subject.  They  fed  a  diet  consisting  of  purified 
protein,  cane  sugar,  starch,  and  "protein-free  milk,"  and  in  some 
of  their  experiments  with  similar  diets  "artificial  protein-free 
milk"  was  used  instead  of  the  natural  product.  The  artificial 
product  was  composed  of  milk  sugar  and  a  salt  mixture  from 
reagent  bottles.  It  was  made  in  close  imitation  of  the  mineral 
content  which  analysis  showed  to  be  present  in  the  natural 
product.  These  diets,  which  contained  no  fats,  were  capable  of 
inducing  normal  growth  for  a  period  of  sixty  days. 

Commenting  on  these  results  Osborne  and  Mendel  stated: 
"Employing  the  methods  which  were  adopted  in  our  earlier  feed- 
ing experiments  with  isolated  food  substances,  we  have  succeeded 
in  inducing  a  normal  rate  of  growth  in  white  rats  with  dietaries 
devoid  of  fat  throughout  almost  the  entire  period  during  which 
growth  ordinarily  continues."  They  stated  that  "McCollum  has 
demonstrated  that  the  phosphorus  needed  by  an  animal  for  phos- 
phatid  formation  can  be  drawn  from  inorganic  phosphates,  and 
that  phosphatids  can  be  synthesized  anew  in  the  animal  body. 
Rohmann  asserts  the  possibility  of  lecithin  synthesis  in  mice 
which  were  maintained  into  the  second  generation  on  lecithin-free 
food.  Our  own  experiments  point  in  the  same  direction  with 
regard  to  the  lipoids  in  general,  and  they  give  positive  evidence 
of  the  dispensableness  of  true  fats  for  growth." 

23.  McCollum  and  Davis  Discover  the  Unique  Dietary 
Properties  of  Butter  Fat  as  Contrasted  with  Vegetable  Fats 
and  Body  Fats, — When  this  paper  appeared  McCollum  had 
already  accumulated  experimental  data  which  led  him  to  believe 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS       21 

that  there  were  very  great  differences  in  the  nutritional  value  of 
fats  from  several  sources.  With  diets  composed  of  protein, 
starch,  milk  sugar,  salts,  and  fats,  it  had  been  found  that  pro- 
longed growth  was  secured  when  butter  fat  was  added.  This 
had  been  dissolved  in  ether  and  passed  through  filter  paper  in 
order  to  make  certain  that  no  traces  of  any  ingredients  of  the 
milk  except  the  fats  and  substances  having  the  same  solubilities 
were  present.  Egg  yolk  fats  behaved  like  the  purified  butter 
fat,  whereas  little  growth  and  early  failure  resulted  when  olive 
oil  or  lard  formed  the  only  fats  in  the  diet.  Owing  to  an  epi- 
demic which  destroyed  the  rat  colony  a  year  elapsed  before  a 
fairly  satisfactory  demonstration  of  this  fact  could  be  secured, 
the  records  of  which  seemed  safe  for  publication.  In  June,  1913, 
McCollum  and  Davis  (8)  recorded  their  findings  that  carefully 
purified  butter  fat,  all  of  which  was  soluble  in  fat  solvents,  and 
likewise  egg  yolk  fat,  contained  something  which  greatly  pro- 
moted growth,  and  that  lard  and  olive  oil  did  not  possess  this 
property. 

24.  Osborne  and  Mendel's  Observations  on  Butter. — Os- 
borne  and  Mendel  had  discovered  by  this  time  the  error  of  their 
conclusion  that  growth  and  well-being  could  be  secured  in  ani- 
mals restricted  to  a  diet  free  from  fats  and  containing  "but  an 
insignificant  trace  of  ether  extract."  The  month  following  the 
appearance  of  the  paper  by  McCollum  and  Davis  demonstrating 
the  peculiar  value  of  certain  animal  fats  as  contrasted  with 
other  animal  fats  and  with  vegetable  fats  (8) ,  Osborne  and  Men- 
del published  a  paper  on  "The  Relation  of  Growth  to  the  Chemi- 
cal Constituents  of  the  Diet"  (3) .  They  described  in  this  paper 
the  preliminary  period  of  growth  they  secured  with  their  diet  of 
purified  protein,  starch,  sugar,  and  "protein-free  milk."  This 
short  period  of  growth,  which  rarely  extended  beyond  sixty  days, 
was  followed  by  decline.  The  decline,  they  found,  could  be 
checked  by  the  addition  of  16.4  per  cent  of  butter.  Animals 
which  received  the  butter  from  the  beginning  of  the  experiment 
grew  uninterruptedly  to  maturity  or  nearly  so.  In  their  paper 
on  nutrition  with  fat-free  food-stuffs  they  had,  curiously  enough, 
interrupted  their  experiments  at  the  end  of  sixty  days  or  there- 
abouts from  the  time  when  the  animals  were  restricted  to  the 
"protein-free  milk"  and  "artificial  protein-free  milk"  mixtures, 
and  yet  they  described  these  records  as  successful  growth 
"through  almost  the  entire  period  during  which  growth  ordinarily 
continues." 

It  was  not  possible  to  draw  any  conclusions  from  the  data 


22       THE  NEWER  KNOWLEDGE  OF  NUTRITION 


presented  in  their  paper  now  under  discussion  as  to  whether  the 
unknown  food  complex  present  in  butter  was  in  the  fat  fraction 
or  in  the  non-fat  fraction  of  the  latter.  Butter  contains  about 
15  per  cent  of  milk  substance  other  than  fat.  This  portion  con- 
sists, among  other  things,  of  water,  protein,  cells  from  the  mam- 
mary gland,  leucocytes,  and  bacteria,  and  it  was  impossible  to 
decide  without  further  evidence  whether  it  was  in  some  of  these 
or  in  the  fat  itself  that  the  substance  occurred  which  exerted 
such  remarkable  effects  on  the  growth  of  animals.  Hopkins  (9) 
had  just  reported  that  rats  restricted  to  diets  of  purified  food- 
stuffs steadily  declined,  whereas  similar  ones  which  were  con- 
fined to  the  same  diets,  but  in  addition  received  1  to  3  c.c.  per 
day  of  fresh  milk  were  able  to  grow.  Even  after  decline  had 
set  in  on  the  basal  diet  it  could  be  checked  by  this  small  quantity 
of  milk,  which  in  no  instance  exceeded  about  4  per  cent  of  the 
dry  weight  of  the  diet. 

CHART  I 
Journal  of  Biol.  Chem.,  1913,  xv,  167 


260 


.240 


220 


200 


160 
160 
140 
120 
100 
80 
60 
40 


10        12 


16        16       2,0       22       24       26     25 


Chart  1  shows  one  of  the  original  growth  curves  published  by 
McCollum  and  Davis,  which  led  them  to  the  discovery  of  the 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        23 

special  growth-promoting  properties  of  butter  fat  as  contrasted 
with  vegetable  fats  and  certain  animal  fats. 

CHART  I  (Rat  141,  male)  shows  the  record  of  a  rat  which  grew 
continuously  although  slightly  under  normal  rate  during  eighty 
days  on  a  ration  of  relatively  pure  food  substances.  There  was 
at  this  time  a  complete  suspension  of  growth  and  a  rapid  decline 
in  body  weight.  The  addition  of  10  per  cent  of  ether-soluble 
butter  fat  to  the  diet  led  to  a  prompt  resumption  of  growth  dur- 
ing the  following  thirty-five  days,  when  the  rat  gained  50  grams. 

The  rations  employed  were  as  follows: 

PERIOD  I  PERIOD  II  PERIOD  III 

per  cent  per  cent 

Salt  mixture  6  Salt  mixture    5       Same  as  II  with  butter 

Casein    12  Casein    12          fat  replacing  part  of 

Lard   20  Lactose    20          dextrin. 

Lactose   15  Dextrin    61 

Starch   42  Agar-agar    2 

Agar-agar    5 

The  salt  mixture  employed  consisted  of: 

grama  grams 

Sodium  chlorid    0.61      Calcium   lactate    11.38 

Dipotassium  phosphate  17.00  Magnesium   citrate ( 10.2% Mg)  23.42 

Monocalcium  phosphate 1.63      Ferric  citrate    1.00 

The  lactose  in  the  diet  was  not  entirely  pure,  and  contained 
enough  of  the  water-soluble  B  to  support  growth. 

25.  Osborne  and  Mendel's  Studies  on  Butter  Fat  and 
Other  Fats. — Five  months  later  Osborne  and  Mendel  (10)  de- 
scribed experiments  entirely  analogous  to  those  of  McCollum 
and  Davis,  in  which  their  animals  were  confined  to  purified  pro- 
tein, starch,  "protein-free  milk/'  lard  and  butter  fat. 

Although  the  final  evidence  which  Osborne  and  Mendel  offered 
as  proof  of  the  unsuspected  value  of  butter  fat  in  nutrition  was 
of  the  same  kind  as  had  been  presented  five  months  earlier  by 
McCollum  and  Davis,  in  which  butter  fat  and  egg  yolk  fat  were 
shown  to  be  similar,  and  superior  to  lard  or  olive  oil,  their  paper 
attempted  to  minimize  the  importance  of  the  work  of  McCollum 
and  Davis.  They  stated  that  "In  none  of  their  (McCollum  and 
Davis)  published  records  was  the  recovery  so  rapid  as  in  most 
of  ours,  nor  was  the  rate  or  extent  of  growth,  after  reaching  the 
previous  maximum  weight,  any  greater  than  on  the  butter  fat- 
free  diet  earlier  supplied."  Further,  "although  the  data  furnished 
by  McCollum  and  Davis  strongly  indicate  that  butter  fat  has  a 
marked  influence  on  growth,  they  by  no  means  prove  that  butter 


24      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

fat  contains  something  essential  for  the  metabolism  of  growth 
apart  from  that  of  maintenance." 

It  is  now  clear  that  the  reason  for  the  better  growth  of  Osborne 
and  Mendel's  animals  when  butter  fat  was  added  to  the  diet 
was  due  to  the  fact  that  their  "protein-free  milk"  contained  an 
abundance  of  a  second  dietary  factor,  the  anti-neuritic  substance 
which  prevents  beri-beri,  whereas  the  diets  of  McCollum  and 
Davis  contained  decidedly  less  of  this  substance  which  was 
present  as  an  impurity  in  the  supposedly  pure  milk  sugar  which 
their  diet  contained.  It  seems  certain  that  there  is  no  substance 
essential  for  maintenance,  apart  from  growth,  as  the  last  quoted 
sentence  suggests.  This  idea  has  been  in  the  minds  of  several 
investigators,  but  the  evidence  that  normal  maintenance  can  be 
secured  on  any  diet  lacking  in  a  complex  necessary  for  growth 
is  very  slender  indeed.  This  point  will  be  discussed  in  Chap- 
ter III. 

Early  in  1914  Osborne  and  Mendel  (11)  confirmed  the  ob- 
servation of  McCollum  and  Davis  that  egg  yolk  fats  and  cod 
liver  oil  had  the  same  effect  on  growth  that  butter  fat  exerted, 
and  that  lard  did  not  stimulate  growth  as  did  egg  and  milk  fats. 
They  investigated  almond  oil  and  found  it  to  resemble  olive  oil 
in  the  respect  that  it  did  not  promote  growth. 

26.  Stepp's  Experiments  on  the  Indispensability  of  Certain 
Lipins  in  Nutrition. — The  results  of  these  investigations  recalled 
the  fact  that  as  early  as  1909  Stepp  (12)  had  described  experi- 
ments in  which  he  had  found  that  bread  prepared  with  milk 
was  capable  of  maintaining  adult  white  mice  without  loss  of 
weight  for  an  indefinite  period.    When  the  same  bread  was  ex- 
tracted with  alcohol-ether,  the  animals  restricted  to  it  rapidly 
declined.    Replacement  of  the  extracted  material  failed  to  restore 
the  dietary  properties  of  the  original  bread.    In  later  experi- 
ments Stepp  showed  that  the  addition  of  the  salts  which  were 
extracted  with  the  lipoids  did  not  prevent  the  rapid  decline  of  the 
animals.    Butter  additions   did  not  prevent  decline,   but  the 
addition  to  the  extracted  bread,  of  lipin  extracts  of  egg  yolk, 
bran,  dry  milk  or  wheat,  restored  the  extracted  bread  to  dietary 
completeness. 

27.  Osborne  and  Mendel's  Experience  with  "Artificial  Pro- 
tein-Free Milk." — It  has  been  pointed  out  that  students  of  normal 
nutrition  failed  to  make  use  of  the  observations  of  the  patholo- 
gists  during  the  decade  between  1905  and  1915.    In  discussing  the 
possible  explanation  of  the  early  failure  of  their  animals  fed 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        25 

isolated  food-substances,  together  with  "artificial  protein-free 
milk,"  Osborne  and  Mendel  (13)  emphasized  the  improvement  of 
the  latter  by  the  addition  of  traces  of  manganese,  iodin,  fluorin 
and  aluminum,  and  dwelt  upon  the  possible  importance  of  minor 
variations  in  the  inorganic  moiety  of  the  diet.  Even  at  the  end 
of  1913  (14)  in  commenting  on  McCollum's  studies  of  butter 
fat  they  stated  that  "The  added  butter  fat  may  have  simply 
supplied  something  analogous  to  the  so-called  vitamines,  which 
Funk  considers  to  be  essential  for  life,  and  thereby  enabled  the 
animals  to  resume  growth  on  a  food  thus  made  adequate  for 
maintenance."  Further,  "It  is  still  rather  early  to  generalize 
on  the  role  of  accessory  Vitamines7  when  the  ideal  conditions 
in  respect  to  the  familiar  fundamental  nutrients  and  inorganic 
salts  adequate  for  prolonged  maintenance  are  not  completely 
solved."  These  quotations  will  serve  to  show  that  these  investi- 
gators were  likewise  in  the  same  state  of  confusion  as  to  the 
interpretation  of  the  data  in  the  literature  of  pathology  which 
described  the  experimental  production  of  beri-beri  and  of  scurvy 
(15),  as  were  McCollum  and  his  co-workers.  At  the  time  Hop- 
kins published  his  proof  of  the  necessity  of  certain  accessory 
foodstuffs  he  apparently  was  not  aware  of  the  epoch-making 
observations  of  Eijkman  that  a  diet  of  polished  rice  would  induce 
polyneuritis  in  birds  and  that  the  rice  polish  contained  something 
which  would  relieve  the  condition  (9). 

28.  The  Confusion  Concerning  the  Essential  Nutritive  Fac- 
tors Previous  to  1915. — It  is  easy  now  to  see  in  the  light  of  later 
experience  why  such  skepticism  existed  regarding  the  necessity 
of  hitherto  unappreciated  factors  in  the  diet.  Osborne  and 
Mendel  and  McCollum  had  seen  young  rats  grow  for  a  consid- 
erable time  when  restricted  to  diets  of  supposedly  pure  food 
substances.  These  substances,  however,  always  contained  a  con- 
siderable amount  of  lactose  or  milk  sugar,  and  it  was  not  appre- 
ciated at  the  time  that  impurities  of  a  most  important  nature 
might  still  adhere  to  lactose  of  a  relatively  high  degree  of  purity. 

When  it  was  found  in  1913  that  the  addition  of  butter  fat  pro- 
moted growth  on  a  diet,  which  consisted  aside  from  this  fat 
only  of  substances  of  accepted  purity,  every  component  of  the 
diet  being  regarded  as  known  chemically,  it  seemed  very  plaus- 
ible that  the  only  unidentified  dietary  essential  for  the  rat  was 
associated  with  the  fat  fraction.  This  view  was  at  one  time 
held  by  McCollum.  In  all  such  studies  the  question  as  to  the 
degree  of  purity  of  each  of  the  ingredients  of  the  diet  necessary 


26       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

to  warrant  the  conclusion  that  no  impurities  of  a  significant 
nature  were  present  could  be  decided  only  through  critical  and 
comparative  experiments. 

29.  How  the  Problem  Was  Cleared  Up. — The  manner  in 
which  the  problem  was  finally  cleared  up  as  to  the  number  of 
unidentified  factors  the  diet  must  contain  in  addition  to  the  long 
recognized  fundamental  nutrients,  protein,  carbohydrate,  fat  and 
mineral  salts,  is  of  historical  interest.     During  the  years  between 
1913  and  1918  Osborne  and  Mendel,  and  McCollum  and  his 
co-workers   confined  their  researches   to   different   fields.    The 
former  two,  believing  that  their  diet  containing  a  purified  pro- 
tein and  other  isolated  food-stuffs,  supplemented  with  28  per 
cent  of  "protein-free  milk,"  was  satisfactory  for  the  study  of 
the  comparative  values  of  the  proteins  from  various  sources,  ex- 
tended their  investigations  in  the  direction  of  determining  the 
biological  value  of  each  of  the  more  important  proteins  isolated 
from  natural  foods.     McCollum  and  his  co-workers  turned  their 
attention  to  the  determination  of  the  nature  from  the  dietary 
standpoint,   of  the  deficiencies  of  our  natural   foods.     It  was 
through  these  studies  that  the  next  advance  was  gained  in  our 
knowledge  of  what  constitutes  a  satisfactory  diet  for  the  rat. 

30.  McCollum's  Studies  with  Restricted  Rations. — While 
the  studies  with  rations  restricted  to  a  single  plant  source  were 
in  progress  with  cattle  at  the  Wisconsin  Experiment  Station,  Mc- 
Collum, beginning  in  the  year  1907,  restricted  the  diet  of  rats 
to  each  of  the  more  important  single  grains  and  seeds,  fed  as  the 
sole  source  of  nutriment.     It  was  discovered  that  whole  wheat 
alone,  rolled  oats  alone,  maize  kernel,  or  any  other  seed  fed 
alone,  failed  to  induce  any  growth  in  young  animals,  or  to  main- 
tain life  for  a  long  period  of  time.     It  seemed  to  him  in  1913 
after  the  completion  of  the  experimental  studies  described  in 
this  chapter,  that  he  was  in  possession  of  the  necessary  knowl- 
edge to  enable  him  to  determine  the  nature  of  the  faults  respon- 
sible for  these  failures. 

31.  Formulation  of  the  Biological  Method  for  the  Analysis 
of  a  Food-Stuff. — Chemical  analysis  shows  the  cereal  grains  to 
contain  all  the  essential  food  substances  for  which  we  know  how 
to  analyze,  and  it  was  assumed  as  a  working  hypothesis  that  the 
only  unknown  factor  contained  in  the  diet  was  that  associated 
with  certain  fats.    The  first  intensive  study  was  made  on  the 
wheat  kernel.     It  was  reasoned  that  since  all  the  types  of  nutri- 
ents are  represented  in  a  seed  such  as  the  wheat  kernel,  except 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        27 

possibly  the  unknown  one  which  had  been  demonstrated  to  be 
present  in  certain  fats,  the  fault  or  faults  of  wheat  from  the 
dietary  standpoint  must  lie  in  the  quality  of  one  or  more  of  these 
food  factors.  It  was  reasoned  that  valuable  data  might  be  se- 
cured by  enhancing  the  protein,  the  inorganic  moiety  and  the  fat 
factors  separately  in  feeding  experiments.  It  seemed  possible 
to  discover  by  means  of  a  systematic  series  of  feeding  experi- 
ments in  which  the  quality  of  the  seed  should  be  improved  with 
respect  to  one  dietary  factor  at  a  time,  which  factor  was  inter- 
fering with  growth  (16).  Accordingly  McCollum  and  Davis 
fed  the  wheat  kernel  in  the  following  combinations,  and  obtained 
the  results  noted: 

1.  Wheat  alone  .  .  .  No  growth,  short  life. 

2.  Wheat  plus  purified  protein  .  .  .  No  growth,  short  life. 

3.  Wheat  plus  a  salt  mixture  which  gave  it  a  mineral  content  similar  to 

that  of  milk  .  .  .  Very  little  growth. 

4.  Wheat  plus  a  growth  promoting  fat  (butter  fat)  .  .  .  No  growth. 

From  these  results  it  seemed  apparent  that  either  the  working 
hypothesis  regarding  the  factors  which  are  necessary  in  the  diet 
must  be  wrong,  or  there  must  be  more  than  a  single  dietary 
factor  deficient  in  wheat,  and  jointly  responsible  for  the  poor 
nutrition  of  the  animals.  In  order  to  test  this  theory  another 
series  of  experiments  were  carried  out,  in  which  wheat  was  sup- 
plemented with  two  purified  food  additions: 

5.  Wheat  plus  protein,  plus  the  salt  mixture  .  .  .  Good  growth  for  a  time. 

Few  or  no  young.    Short  life. 

6.  Wheat  plus  protein,  plus  a  growth  promoting  fat  (butter  fat)  .  .  .  No 

growth.    Short  life. 

7.  Wheat  plus   the   salt   mixture,   plus  a   growth   promoting   fat    (butter 

fat)  ...  Fair  growth  for  a  time.    Few  or  no  young.    Short  life. 

The  behavior  of  the  animals  fed  wheat  with  two  purified  food 
additions  was  highly  suggestive  that  there  are  three  dietary 
factors  of  poor  quality  in  the  wheat  kernel.  This  was  demon- 
strated to  be  true  by  a  feeding  trial  in  which  wheat  was  fed, 
supplemented  with  three  purified  food  additions: 

8.  Wheat  plus  protein,  plus  the  salt  mixture,  plus  a  growth  promoting  fat 

(butter  fat)  .  .  .  Good  growth,  normal  number  of  young,  good  success 
in  rearing  young.    Life  approximately  the  normal  span.    See  chart  2. 

McCollum  and  Davis  were,  in  1914,  more  than  ever  convinced 
that  the  only  element  of  mystery  in  the  normal  diet  was  the 
unidentified  substance  in  butter  fat,  for  with  the  improvement  of 
three  dietary  factors  wheat  became  a  satisfactory  food  for  the 


I    E    I    8    8    5 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        29 

nutrition  of  an  animal  during  growth,  and  for  the  support  of 
all  the  functions  of  reproduction  and  rearing  of  young. 

32.  Two  New  Viewpoints  in  Nutrition. — This  series  of  ex- 
periments brought  to  light  two  new  viewpoints  in  nutrition,  one 
of  which  was — that  the  inorganic  content  of  the  wheat  kernel, 
although  it  furnishes  all  the  necessary  elements,  does  not  contain 
enough  of  certain  of  these  to  meet  the  requirements  of  a  young 
animal  during  the  growing  period.    It  is  true  that  some  years 
earlier  Henry  (17)  had  called  attention  to  the  deficiency  of  the 
corn  kernel  in  ash  content  and  had  in  some  of  his  experiments 
added  wood  ashes  to  the  diet,  with  noticeable  improvement  in  the 
well-being  of  the  animals.    The  fact  that  seeds,  such  as  wheat, 
fail  to  supply  enough  of  any  of  the  essential  inorganic  elements 
was  not  generally  appreciated  and  was  given  but  little  attention 
in  books  on  nutrition.    Later,  work  by  McCollum  and  Simmonds 
demonstrated  that  the  deficiency  in  mineral  elements  in  wheat 
and  other  seeds  is  limited  to  four  elements,  calcium,  phosphorus, 
sodium  and  chlorin  (18). 

A  second  new  viewpoint  brought  out  by  these  experiments 
was  the  fact  that  the  wheat  kernel  is  indeed  too  poor  in  its  con- 
tent of  the  unidentified  substance  which  butter  fat  contains  to 
nourish  satisfactorily  an  animal  over  a  long  period  of  time. 

33.  Proteins  Not  All  Constituted  Alike. — It  has   already 
been  mentioned  that  the  studies  of  Kossel,  Fischer  and  of  Os- 
borne  had  made  it  clear  that  there  should  exist  very  pronounced 
differences  in  the  value  of  the  proteins  from  different  sources. 
The  proteins  were  prepared  in  a  state  of  relative  purity  and 
were  digested  in  the  laboratory  by  means  of  acids,  and  were 
analyzed  by  the  methods  of  Fischer  and  of  Kossel.    Certain  of 
the  eighteen  digestion  products,  the  amino-acids,  were  deter- 
mined quantitatively  so  far  as  the  methods  would  permit.    Al- 
though the  technique  was  never  perfected  so  as  to  give  results 
approximately  quantitative,  except  in  the  case  of  less  than  a 
third  of  the  amino-acids  known  to  be  formed  in  the  digestion 
of  proteins,  it  was  shown  in  the  case  of  these  few  amino-acids 
that  there  were  very  great  variations  in  the  proportions  among 
them  in  the  mixtures  obtained  from  proteins  of  different  sources. 
Thus  the  proteins  of  the  muscle  tissues  of  several  species  of  ani- 
mals were  shown  to  yield  between  12  and  14  per  cent  of  glutamic 
acid,  one  of  the  products  of  hydrolysis  obtained  from  practically 
all  proteins.    The  same  amino-acid  is  present  in  the  two  prin- 
cipal proteins  of  the  wheat  kernel  to  the  extent  of  about  40  per 


30       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

cent  of  the  total  protein  content.  These  two  proteins  together 
make  about  85  per  cent  of  the  total  protein  of  the  wheat  kernel. 
Other  equally  great  differences  were  shown  to  exist  in  the  com- 
position of  proteins  of  our  common  food-stuffs,  and  those  of  the 
tissue  proteins  formed  during  growth. 

34.  The  Problem  which  an  Animal  Meets  in  Its  Protein 
Nutrition. — A  good  illustration  of  the  problems  which  the  ani- 
mal meets  in  its  protein  nutrition  may  be  had  by  comparing  the 
digestion  products  of  the  protein  molecule  to  the  letters  of  the 
alphabet.  The  proteins  of  the  food  and  of  the  tissues  may  be 
regarded  as  made  up  of  the  same  letters  arranged  in  different 
orders  and  present  in  different  proportions.  In  growth  the  ani- 
mal takes  as  food,  proteins  which  are  very  unlike  those  of  its 
tissues,  splits  these  into  the  simple  compounds,  the  amino-acids, 
and  then,  after  absorbing  these,  puts  together  the  fragments  in 
new  order,  and  in  new  proportions  to  form  the  tissue  proteins. 

If  the  muscle  tissue  of  an  animal  be  likened  to  a  block  of 
printer's  type  so  arranged  as  to  print  the  rhyme  beginning  "Jack 
Spratt  could  eat  no  fat,  and  his  wife  could  eat  no  lean,"  the 
proteins  of  which  the  muscle  consists  are  represented  by  the 
individual  words,  and  the  protein  digestion  products  by  the  let- 
ters of  which  the  words  consist.  Now  if  the  animal  should  take 
food  proteins  which  correspond  to  a  block  of  type  which  would 
print  the  jingle  beginning  "Peter  Piper  picked  a  peck  of  pickled 
peppers,"  it  is  easy  to  understand  that  when  the  proteins  of  the 
food  are  resolved  into  their  constituent  letters,  and  an  effort 
made  to  form  the  body  proteins  of  the  new  and  different  type 
from  the  letters  supplied  by  the  food,  the  transformation  can- 
not be  made.  In  setting  up  the  first  line,  "Jack  Spratt  could 
eat  no  fat  and  his  wife  could  eat  no  lean,"  we  need  four  of  the 
letter  t,  but  the  food  proteins  contain  but  one.  The  first  line 
of  the  Jack  Spratt  rhyme,  which  represents  the  muscle  proteins, 
requires  but  one  letter  p,  whereas  the  food  proteins  expressed  by 
the  Peter  Piper  rhyme  yield  nine  in  the  first  line.  The  first  line 
of  the  Jack  Spratt  rhyme  contains  the  letters  j  and  n,  whereas 
the  Peter  Piper  rhyme  contains  none,  so  that  even  with  the 
entire  stanza: 

Peter  Piper  picked  a  peck  of  pickled  peppers, 
If  Peter  Piper  picked  a  peck  of  pickled  peppers, 
Where's  the  peck  of  pickled  peppers 
That  Peter  Piper  picked? 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        31 

it  is  not  possible  to  reproduce  even  the  first  line  of  the  Jack 
Spratt  rhyme,  and  in  order  that  growth  might  become  possible 
it  would  be  necessary  to  take  proteins  of  another  character  which 
would  supply  the  missing  letters. 

Such  a  comparison  between  food  proteins  and  tissue  proteins 
gives  a  good  illustration  of  the  kind  of  problem  which  the  animal 
meets  in  its  protein  nutrition.  The  most  conspicuous  protein 
of  the  corn  kernel,  zein,  is  wholly  lacking  in  three  of  the  amino- 
acids  or  digestion  products  which  are  obtainable  from  most  tissue 
proteins.  In  accord  with  what  we  should  expect  on  theoretical 
grounds,  this  protein  is,  when  taken  as  the  sole  source  of  amino- 
acids,  not  capable  of  supporting  growth,  or  of  maintaining  an 
animal  in  body  weight.  This  illustration  shows  how  we  may 
have  superior,  good  or  inferior  food  proteins  for  the  formation 
of  body  proteins  in  growth. 

35.  The  Biological  Analysis  of  Polished  Rice. — The  inves- 
tigations, the  object  of  which  was  to  find  the  cause  of  the  failure 
of  an  animal  to  grow  when  restricted  to  wheat  as  its  sole  source 
of  nutriment,  were  carried  out  in  1913,  soon  after  the  publication 
by  Funk  of  his  first  work  on  poly  neuritis.  In  the  same  year 
Hopkins  called  attention  to  the  remarkable  effects  produced  by 
the  addition  of  small  amounts  of  milk  to  diets  composed  of 
purified  food-stuffs.  The  vitamin  hypothesis  had  just  been 
formulated  by  Funk  (19).  McCollum  and  Davis  were,  there- 
fore, aware  of  the  relation  of  a  diet  of  polished  rice  to  experi- 
mental beri-beri.  They  believed,  in  the  light  of  their  experiences 
with  the  diet  of  purified  protein,  milk  sugar,  fats  and  inorganic 
salts,  that  such  a  mixture  was  capable  of  inducing  growth  when 
certain  fats  were  supplied,  but  not  when  others  were  substituted. 
The  further  fact  that  wheat  could  be  supplemented  by  purified 
protein,  a  growth-promoting  fat,  and  a  suitable  salt  mixture, 
that  is,  with  food-stuffs  of  known  character,  seemed  to  indicate 
that  there  was  but  a  single  unidentified  substance  necessary  in 
the  diet.  They  decided  to  apply  to  polished  rice  the  same  pro- 
cedure which  had  shown  so  clearly  the  nature  of  the  dietary 
deficiencies  of  wheat.  Rice,  they  reasoned,  could  be  nothing  less 
than  a  mixture  of  proteins,  starch,  fat,  and  of  inorganic  salts, 
similar  to  that  contained  in  wheat,  but  in  different  proportions. 
It  should,  therefore,  be  supplemented  with  a  suitable  salt  mix- 
ture, a  purified  protein,  and  a  growth-promoting  fat,  so  as  to 
induce  growth  and  maintain  animals  for  a  long  time  in  a  state 
of  health.  This  seemed  to  be  a  necessary  corollary,  since  they 


32       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

had  secured  growth  and  well-being  in  animals  fed  strictly  upon 
a  mixture  of  purified  protein  (casein) ,  starch,  milk  sugar,  butter 
fat  and  a  mixture  of  inorganic  salts  of  suitable  composition  (20) . 

It  was  a  great  surprise  to  McCollum  and  Davis  to  find  that 
polished  rice,  even  when  supplemented  with  the  purified  protein, 
casein,  butter  fat  and  a  salt  mixture  properly  constituted,  failed 
utterly  to  induce  any  growth  in  young  rats  (21).  Not  only  did 
they  fail  to  grow,  but  in  the  course  of  a  few  weeks  they  developed 
in  some  cases  a  state  of  paralysis  which  was  suggestive  of  poly- 
neuritis.  Here  was  an  apparent  contradiction.  The  polished 
rice  could  be  nothing  less  than  a  mixture  of  protein,  carbohydrate, 
fat  and  salts.  The  only  difference  between  this  and  the  mixture 
of  supposedly  purified  food-stuffs  with  which  they  had  achieved 
success  was  in  the  20  per  cent  of  milk  sugar  which  the  synthetic 
diet  contained.  They,  therefore,  decided  to  repeat  the  experi- 
ments with  the  latter  mixture,  with  the  milk  sugar  replaced  by 
starch.  It  was  found  that  this  change  in  the  composition  of 
the  food  mixture  made  the  difference  between  success  and  failure. 
No  growth  could  be  secured  when  the  milk  sugar  was  omitted. 
Later  experiments  showed  that  if  milk  sugar  sufficiently  purified 
by  repeated  crystallization  was  added  to  the  purified  food  mix- 
ture it  was  no  longer  effective  in  inducing  growth  whereas  the 
water  from  which  the  sugar  had  been  crystallized  would,  when 
evaporated  upon  the  food  mixture,  render  it  capable  of  inducing 
growth.  This  made  it  evident  that  there  is  indeed  a  second 
dietary  essential,  of  which  an  animal  needs  but  a  very  small 
amount,  but  which  is  absolutely  necessary  for  both  growth  in 
the  young  and  for  the  maintenance  of  health  in  the  adult. 

36.  Demonstration  of  the  Necessity  of  Two  Vitamins  in  the 
Nutrition  of  the  Rat. — Further  experiments  were  then  conducted 
to  find  whether  this  unidentified  substance  which  was  being 
added  accidently  as  an  impurity  in  the  milk  sugar  was  the  same 
as  the  substance  with  which  Funk  and  others  were  dealing  in 
their  studies  of  beri-beri.  It  was  found  that  pigeons  which  had 
developed  beri-beri  as  the  result  of  being  fed  exclusively  upon 
polished  rice  could  be  temporarily  "cured"  with  any  preparation 
which  would,  when  added  to  a  diet  of  purified  food-stuffs  con- 
taining a  growth-promoting  fat,  cause  animals  to  grow.  See 
chart  3. 

Following  the  method  of  Funk  and  Suzuki,  McCollum  and 
Davis  in  1914  employed  alcoholic  extracts  of  various  natural 
foods,  adding  the  alcohol-soluble  matter  to  the  standard  mixture 


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34       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

of  purified  protein  (casein) ,  starch  (dextrinized) ,  salts  and  butter 
fat,  and  soon  became  convinced  that  the  substance  which  relieves 
polyneuritis  in  pigeons  was  always  present  in  the  preparations 
which  rendered  the  diet  of  purified  food-stuffs  capable  of  pro- 
moting growth.  An  alcoholic  extract  of  ether  extracted  wheat 
germ  was  finally  adopted  as  a  source  of  this  dietary  factor  in 
later  investigations.  Funk  and  his  co-workers  had  previously 
shown  that  the  curative  substance  is  present  in  many  natural 
foods  (19).  Repeated  experiments  by  McCollum  and  Davis 
showed  that  the  inclusion  of  the  alcoholic  extract  of  wheat  germ 
or  of  other  food  was  not  sufficient  to  induce  growth  unless  the 
butter  fat  or  other  similar  fat  was  likewise  added  to  the  purified 
food  mixture.  Both  the  growth-promoting  fat  and  the  trace 
of  unidentified  substance  in  the  alcoholic  extract  of  wheat  germ 
are  necessary  for  the  promotion  of  growth  or  the  preservation 
of  health  (22). 

37.  Funk  and  Macallum  Report  that  Butter  Fat  Contained 
No  Vitamine. — Funk  and  Macallum  found  butter  fat  ineffective 
for  the  cure  of  polyneuritis  in  pigeons,  and  accordingly  con- 
sidered it  free  from  "vitamine."    They  fed  young  rats  a  diet  of 
purified  food-stuffs  supplemented  with  a  liberal  amount  of  butter 
fat,  and  found  that  the  animals  did  not  grow.    Although  this 
was  the  result  of  the  lack  of  the  anti-neuritic  substance,  they  were 
not  at  that  time  'clear  as  to  the  several  factors  which  are  neces- 
sary in  the  diet  and  interpreted  their  data  as  evidence  that  butter 
fat  possessed  no  growth-promoting  properties  (23). 

38.  McCollum  and  Davis  Formulate  an  Hypothesis  Re- 
garding the  Essentials  of  an  Adequate  Diet. — As  a  result  of 
these  experiments  McCollum  and  Davis  (22)  formulated  in  1915 
their  working  hypothesis  of  what  constitutes  an  adequate  diet. 
The  diet  must  contain,  in  addition  to  the  long  recognized  dietary 
factors,  viz.,  protein,  a  source  of  energy  in  the  form  of  proteins, 
carbohydrates  and  fats;  a  suitable  supply  of  certain  inorganic 
salts,  two  as  yet  unidentified  substances  or  groups  of  substances. 
One  of  these,  fat  soluble  A,  is  associated  with  certain  fats,  and  is 
especially  abundant  in  butter  fat,  egg  yolk  fats,  cod  liver  oil 
and  the  fats  of  the  glandular  organs  such  as  the  liver  and  kidney, 
but  is  absent  or  present  in  but  traces  in  fats  or  oils  of  vegetable 
origin.    The  second  substance,  water-soluble  B,  is  never  asso- 
ciated with  fats  or  oils  of  either  animal  or  vegetable  origin.     It 
is  widely  distributed  in  natural  foods,  and  can  be  isolated  in  a 
concentrated,  but  not  in  a  pure  form,  from  natural  food-stuffs 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        35 

by  extraction  with  either  water  or  dilute  alcohol.  This  water 
or  alcoholic  extract  always  contains  the  substance  which  cures 
polyneuritis. 

39.  Two  Vitamins  Necessary  for  Nutrition  of  the  Rat  and 
Three  for  Man,  Monkey  and  Guinea  Pig. — This  statement  of 
the  deductions  which  it  seemed  justifiable  to  draw  from  the  ex- 
perimental evidence  at  hand  in  1915  can  be  applied  to-day  to  the 
nutrition  of  the  rat.     It  has,  however,  been  found  that  there 
exists  a  third  dietary  essential  which  appears  not  to  be  necessary 
in  the  food  of  the  rat,  but  is  indispensable  in  the  diet  of  man, 
monkey  and  the  guinea  pig.    This  is  a  substance  which  protects 
against  the  syndrome  of  scurvy.    It  will  be  discussed  at  length 
in  Chapter  VIII. 

From  what  has  been  said  of  the  experimental  studies  which 
ultimately  led  to  the  conception  that  there  were  necessary  two 
uncharacterized  dietary  essentials  in  addition  to  the  long  recog- 
nized food  principles  in  the  diet  of  the  rat,  it  will  be  appreciated 
that  about  1914-15  there  were  suggestions  of  various  kinds  "in 
the  air,"  and  that  the  time  had  arrived  when  some  one  of  the 
several  investigators  working  in  the  field  would  soon  formulate 
on  the  basis  of  definite  experimental  evidence  a  working  hypoth- 
esis concerning  the  essentials  of  an  adequate  diet.  Thus  in 
November,  1914,  Mendel,  in  his  Harvey  lecture,  said,  "It  is  not 
unlikely — to  speak  conservatively — that  there  are  at  least  two 
'determinants'  in  the  nutrition  of  growth.  One  of  these  is  fur- 
nished by  our  'protein-free  milk/  which  insures  proper  main- 
tenance even  in  the  absence  of  growth.  .  .  .  Without  this  'de- 
terminant' .  .  .  the  special  components  of  butter  fat  or  cod  liver 
oil  or  egg  fat  induce  only  limited  gains  at  best.  Another  'deter- 
minant' is  furnished  by  these  natural  fats.  Either  of  the  de- 
terminants may  become  'curative';  both  are  essential  for  growth 
when  the  body's  store  of  them  (if  such  there  be)  becomes  de- 
pleted. It  is  too  early  to  attempt  a  tenable  conclusion"  (11). 

40.  Stepp  Failed  to  Interpret  Correctly  His  Results. — Stepp 
was  unable  to  detect  any  special  dietary  property  in  butter  fat, 
while  he  could  easily  do  so  when  alcoholic  extracts  of  certain 
natural  foods  were  used.    This  is  now  readily  understandable. 
His  alcoholic  extracts  contained  some  of  both  the  uncharacter- 
ized substances  discussed  above,  whereas  butter  fat  contains  but 
one.    The  latter,  without  a  supplementary  source  of  the  second 
one  of  these  dietary  factors  would  permit  of  failure  of  the  ex- 
perimental animals. 


36       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

41.  The  Biological  Method  for  Analysis  of  a  Food-Stuff 
Useful  in  Estimating  Vitamins. — The  biological  method  for 
the  analysis  of  a  food-stuff  was  first  developed  with  a  view  to 
discovering  the  nature  of  the  deficiencies  of  individual  natural 
food-stuffs.    For  this  purpose  the  food  under  investigation  is  the 
principal  component  of  the  diet  and  is  supplemented  with  small 
additions  of  one  or  more  purified  food  substances  (e.g.,  protein, 
inorganic  salts,  vitamins),  in  order  to  bring  to  light  the  nature 
of  the  additions  which  enhance  its  value.    The  method  is  applic- 
able in  another  modification,  however,  which  has  yielded  much 
valuable  information  concerning  the  relative  values  of  many  of 
our  more  important  foods  with  respect  to  any  one  dietary  con- 
stituent. 

The  last  mentioned  application  of  the  method  involves  the 
conduct  of  feeding  experiments  in  which  a  basal  food  mixture 
is  employed  which  is  entirely  satisfactory  as  a  source  of  nutri- 
ment for  a  growing  animal  except  that  it  lacks  entirely  a  single 
dietary  essential.  For  example  a  mixture  of  purified  protein, 
carbohydrate,  an  adequate  salt  mixture  and  a  fat  containing  fat- 
soluble  A,  constitutes  a  diet  which  is  complete  for  the  rat  with 
the  exception  of  lack  of  the  anti-neuritic  substance,  water-soluble 
B.  If  experiments  are  conducted  with  such  a  food,  supplemented 
with  minimal  additions  of  some  natural  food  whose  value  as  a 
source  of  water-soluble  B  it  is  desired  to  estimate,  it  can  be 
determined  what  is  the  smallest  addition  of  the  food  under  inves- 
tigation which  will  furnish  just  sufficient  of  this  vitamin  to  make 
possible  the  normal  growth  and  satisfactory  maintenance  of  the 
animals.  This  method  was  first  employed  by  McCollum  and 
Davis  (16),  who  determined  that  wheat  germ  was  approximately 
five  to  seven  times  as  valuable  as  a  source  of  water-soluble  B  as 
is  whole  wheat  or  other  cereal.  Their  results  indicated  that  the 
cereal  grains  are  essentially  on  a  parity  with  respect  to  their  con- 
tent of  this  substance,  and  are  somewhat  inferior  to  alfalfa  leaves 
in  this  respect.  In  a  similar  manner,  if  the  basal  diet  be  made 
complete  except  for  fat-soluble  A,  the  method  may  be  satisfac- 
torily employed  for  comparing  the  content  of  this  substance  in 
a  series  of  natural  foods.  To  this  end  they  are  each  fed  with 
the  basal  ration,  the  amount  added  being  adjusted  in  a  series 
of  experiments  so  as  to  find  the  least  amount  which  completes 
the  ration  and  induces  normal  nutrition. 

42.  The  Nomenclature  of  the  Vitamins. — The  nomenclature 
of  these  recently  discovered  nutritive  complexes  is  more  or  less 


BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        37 

in  a  state  of  confusion.  Stepp  (12),  who  is  entitled  to  the  credit 
of  having  first  established  the  indispensability  of  certain  alcohol- 
ether  soluble  substances  in  the  diet,  regarded  them  as  lipins. 
Funk  (19)  designated  a  hypothetical  group  of  protective  sub- 
stances of  unknown  nature  "vitamines."  Hopkins  (9)  after  dis- 
covering the  remarkable  growth-promoting  effects  of  small  addi- 
tions of  milk  to  a  diet  of  purified  food-stuffs,  termed  them  "ac- 
cessory" food  substances. 

There  is  much  reason  to  believe  that  Stepp's  view  that  the 
substances  under  discussion  are  lipins  is  erroneous.  They  are 
associated  with  the  lipins  under  the  conditions  under  which  he 
worked.  The  term  "vitamine"  seems  to  bestow  an  importance 
upon  these  substances  paramount  to  that  of  other  indispensable 
substances.  Such  an  assumption  is  obviously  unwarranted. 
There  is  no  evidence  as  yet  that  any  of  them  are  amines,  and 
indeed  there  are  strong  reasons  for  believing  that  one  at  least, 
that  associated  with  certain  fats,  does  not  contain  nitrogen.  The 
term  amine  has  a  definite  significance  in  organic  chemistry,  and 
it  seems  reasonable  to  insist  that  its  use  should  be  reserved  for 
compounds  containing  an  amino  group.  The  term  "accessory" 
food- stuffs  is  the  least  desirable  of  all,  for  it  uses  the  term  "ac- 
cessory" in  a  sense  exactly  the  opposite  to  its  well  established 
meaning,  that  of  an  agent  acting  in  a  subordinate  way  to  a  prin- 
cipal agent.  There  can  obviously  be  no  room  for  differentiation 
on  a  basis  of  importance  among  a  series  of  indispensable  food 
complexes  which  includes  several  amino-acids,  nine  inorganic  ele- 
ments, a  utilizable  carbohydrate,  and  two  or  more  unidentified 
factors.  The  term  "accessory"  would  be  rightly  used  to  desig- 
nate the  condiments,  such  as  the  various  spices,  which  add  to  the 
acceptability  of  foods. 

When  it  was  established  that  there  are  two  unidentified  factors 
necessary  in  the  nutrition  of  the  rat;  that  one  was  soluble  in  fats 
and  not  in  water,  and  the  other  never  associated  with  fats,  but 
easily  dissolved  out  of  natural  foods  by  water  or  dilute  alcohol, 
it  became  necessary  to  differentiate  between  them  by  names 
which  would  characterize  them.  For  the  reasons  stated,  none 
of  the  terms  in  use  seemed  desirable,  and  it  seemed  to  McCollum 
and  Kennedy  (24)  advisable  to  employ  provisionally  algebraic 
terms,  using  a  prefix  designating  characteristic  solubility.  They 
proposed  the  terms  fat-soluble  A  for  the  factor  carried  by  cer- 
tain fats,  and  water-soluble  B  for  the  factor  which  relieves  the 
paralysis  in  polyneuritic  animals.  These  terms  have  found 


38       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

widespread  acceptance,  but  the  terms  introduced  by  Stepp,  Funk 
and  Hopkins,  are  still  used  by  many,  and  frequently  in  ludicrous 
combinations,  such  as  fat-soluble  A  vitamin;  water-soluble  B 
accessory.  The  lack  of  appreciation  of  fitness,  and  even  of  con- 
sideration of  definition  of  well-established  terms,  which  is  ex- 
hibited by  certain  writers  of  this  branch  of  literature  is  truly 
amazing. 

Upon  the  establishment  of  the  existence  of  an  anti-scorbutic 
substance  Drummond  (25)  designated  it  water-soluble  C.  He 
has  recently  (26)  suggested  that  the  spelling  of  vitamine,  be 
changed  to  vitamin,  and  this  term  be  adopted  to  designate  the 
entire  group  of  chemically  uncharacterized  dietary  essentials. 
This  would  be  in  accord  with  the  nomenclature  of  the  hormones 
and  of  the  alkaloids,  and  indicates  nothing  of  their  chemical 
natures.  This  seems  to  be  a  satisfactory  nomenclature  to  adopt. 


BIBLIOGRAPHY 

1.  Rohmann,  F.:    Ueber  kiinstliche  Ernahrung  von  Maiisen.  Allg.  mediz. 

Zentralztg.,  1908,  No.  9.  Abstract  in  Maly's  Jahresbericht  d.  Thier- 
Chemie,  1908,  xxxviii,  659. 

2.  Osborne,  T.  B.,  and  Mendel,  L.  B.:     Bull.  156,  Part  11,  Pub.  of  the 

Carnegie  Institution  of  Washington,  1911. 

3.  Osborne,  and  Mendel:     The  relation  of  growth  to  the  chemical  con- 

stitution of  the  diet,  Jour.  Biol.  Chem.,  1913,  xv,  311. 

4.  Funk,  C.,  and  Cooper,  E.  A.:     Experiments  on  the  causation  of  Beri- 

beri, Lancet,  1911,  11,  1266. 

5.  Osborne,  and  Mendel:    Bull.  156,  Part  1,  Pub.  Carnegie  Inst.  of  Wash- 

ington, 1911. 

6.  McCollum,  E.  V.,  Halpin,  J.  G.,  and  Drescher,  A.  H.:     Synthesis  of 

Lecithin  in  the  hen  and  the  character  of  the  lecithins  produced, 
Jour.  Biol.  Chem.,  1912,  xiii,  219. 

7.  Osborne,  and  Mendel:     Feeding  experiments  with  fat-free  food  mix- 

tures, Jour.  Biol.  Chem.,  1912,  xii,  81. 

8.  McCollum,  E.  V.,  and  Davis,  M.:     The  necessity  of  certain  lipins  in 

the  diet  during  growth,  Jour.  Biol.  Chem.,  1913,  xv,  167. 

9.  Hopkins,  F.  G.:     Feeding  experiments  illustrating  the  importance  of 

accessory  factors  in  normal  dietaries,  Jour,  of  Physiol.,  1912,  xliv, 
425.  Ibid.  Note  on  the  vitamine  content  of  milk,  Biochem.  Jour., 
1920,  xiv,  721. 

10.  Osborne,  and  Mendel:     The  influence  of  butter  fat  on  growth,  Jour. 

Biol.  Chem.,  1913,  xvi,  423. 

11.  Osborne,  and  Mendel:     The  influence  of  cod  liver  oil  and  some  other 

fats  on  growth,  Jour.  Biol.  Chem.,  1914,  xvii,  401.  Also  Mendel: 
Nutrition  and  Growth.  Jour.  Am.  Med.  Assoc.,  1915,  Ixiv,  1539. 
Harvey  Lectures,  1914-1$, 


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BIOLOGICAL  METHOD  OF  FOOD  ANALYSIS        39 

12.  Stepp,    W.:    Versuche    iiber    Fattening    mit    lipoidfreier    Nahrung, 

Biochem.  Zeitschr.,  1909,  xxii,  452.  Ibid.  Experimentelle  Untersuch- 
ungen  iiber  die  Bedeutung  der  Lipoide  fur  die  Ernahrung,  Zeit.  f. 
Biol.,  1911,  Ivii,  135. 

13.  Osborne,  and  Mendel:     The  relation  of  growth  to  the  chemical  con- 

stituents of  the  diet,  Jour.  Biol.  Chem.,  1913,  xv,  316. 

14.  Osborne,  and  Mendel:     The  influence  of  butter  fat  on  growth,  Jour. 

Biol.  Chem.,  1913,  xvi,  428. 

15.  Hoist,  A.,  und  Frohlich,  T.:     Ueber  experimentellen  Skorbut,  Zeit.  f. 

Hygiene  und  Infektionskrankheiten,  1912,  Ixxii,  1. 

16.  Hart,  E.  B.,  and  McCollum,  E.  V.:     Influence  on  growth  of  rations 

restricted   to   the   corn   or   wheat   grain,   Jour.   Biol.   Chem.,    1914, 

xix,  373. 
McCollum,  and  Davis:    The  influence  of  the  composition  and  amount 

of  the  mineral  content  of  the  ration  on  growth  and  reproduction, 

Jour.  Biol.  Chem.,  1915,  xxi,  615. 
McCollum:     The    supplementary    dietary    relationships    among    our 

natural  foodstuffs,  Harvey  Lecture,  Jan.,  1917.    Jour.  Amer.  Med. 

Assoc.,  1917,  Ixviii,  1379. 

17.  Henry,   W.  A.:    Feeding  bone  meal  and  hard  wood  ashes  to  hogs 

living  on  corn,  Wisconsin  Agric.  Exp.  Sta.  Rep.  1889,  15.  Univ.  of 
Wis.  Agr.  Exp.  Sta.  Bull.,  1890,  No.  25,  3. 

18.  McCollum,  E.  V.,  and  Simmonds,  N.:     The  dietary  properties  of  mix- 

tures of  maize  kernel  and  bean,  Jour.  Biol.  Chem.,  1917,  xxxii,  29. 
Shipley,  P.  G.,  Park,  E.  A.,  McCollum,  E.  V.,  and  Simmonds,  N.: 
Studies  on  experimental  rickets,  iii.  A  pathological  condition  bearing 
fundamental  resemblances  to  rickets  of  the  human  being  resulting 
from  diets  low  in  phosphorus  and  fat-soluble  A:  The  phosphate 
ion  in  its  prevention,  The  Johns  Hopkins  Hospital  Bull.,  1921, 
xxxii,  159. 

19.  Funk:     Results  of  studies  on  vitamines  and  deficiency  diseases  during 

the  years  1913-1915,  Jour.  State  Med.,  1912,  xx,  341 ;  Biochem.  Bull., 
1915,  iv,  304. 

20.  McCollum,  and  Davis:     Nutrition  with  purified  food-substances,  Jour. 

Biol.  Chem.,  1915,  xx,  641. 

21.  McCollum,  and  Davis:    The  nature  of  the  dietary  deficiencies  of  rice, 

Jour.  Biol.  Chem.,  1915,  xxiii,  181. 

22.  McCollum,  and  Davis :    The  essential  factors  in  the  diet  during  growth, 

Jour.  Biol.  Chem.,  1915,  xxiii,  231. 

23.  Funk,  C.,  and  Macallum,  A.  B.:     On  the  probable  nature  of  the  sub- 

stance promoting  growth  in  young  animals,  Jour.  Biol.  Chem., 
1915,  xxiii,  413. 

24.  McCollum,  E.  V.,  and  Kennedy,  C.:     The  dietary  factors  operating  in 

the  production  of  polyneuritis,  Jour.  Biol.  Chem.,  1916,  xxiv,  491. 

25.  Drummond,  J.  C.:     Note  on  the  role  of  the  anti-scorbutic  factor  in 

nutrition,  Biochem.  Jour.,  1919,  xiii,  77. 

26.  Drummond:    The  nomenclature  of  the  so-called  accessory  food  factors 

(vitamines),  Biochem.  Jour.,  1920,  xiv,  660. 


CHAPTER  in 
THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS 

43.  Dr.  Beaumont's  Views  on  Digestion. — Although  food 
constitutes  the  chief  item  in  the  expense  of  living  among  the 
wage-earning  class,  and  is  more  intimately  concerned  with  the 
promotion  of  health  and  strength  than  are  clothing,  shelter  and 
climate,  it  is  only  very  recently  that  any  serious  thought  has 
been  given  to  the  nature  of  food,  and  to  the  processes  which  it 
undergoes  in  being  utilized  for  the  bodily  upkeep.  Man  has 
adjusted  himself  to  such  food  supply  as  he  found  available,  and 
accordingly  latitude,  climate  and  soil  and  proximity  to  large 
bodies  of  water  have  been  the  determining  factors  in  establishing 
his  dietary  habits.  Common  observation  led  to  the  knowledge 
that  people  in  different  regions  lived  on  diets  of  widely  different 
character,  yet  without  any  markedly  different  success  in  physical 
development.  Indifference  to  the  nature  of  the  food  supply,  ex- 
cept as  to  palatability,  was  therefore  natural,  since  there  was 
no  obvious  evidence  that  the  character  of  the  diet  had  anything 
to  do  with  well-being,  provided  a  sufficient  amount  of  food  could 
be  had. 

The  paucity  of  our  knowledge  concerning  nutrition  that  existed 
toward  the  middle  of  the  nineteenth  century  is  well  illustrated 
by  the  views  of  Dr.  William  Beaumont,  a  surgeon  in  the  United 
States  Army,  expressed  in  his  book,  "Physiology  and  Experi- 
ments," published  about  1832.  He  had  the  good  fortune  to  study 
the  processes  of  digestion  with  the  hunter,  Alexis  St.  Martin, 
who  had  a  fistulous  opening  into  the  stomach  as  the  result  of  a 
gunshot  wound.  Beaumont  collected  gastric  juice  from  his  sub- 
ject's stomach  and  studied  its  effect  on  various  foods.  He  also 
introduced  foods  into  the  stomach  and  observed  through  the 
opening,  the  behavior  of  this  organ  during  digestion.  He  stated 
very  definitely  that  he  believed  that  the  views  of  others  to  the 
effect  that  there  are  various  kinds  of  nutrient  substances,  were 
in  error.  In  his  opinion  there  was  but  one  kind  of  food  or  "ali- 
ment" as  he  termed  it.  This  was,  he  believed,  present  in  all 

40 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS     41 

foods,  and  was  simply  dissolved  out  by  the  action  of  the  gastric 
secretion.  Dr.  Beaumont  was  one  of  the  most  progressive  inves- 
tigators of  his  time  (1). 

The  chemistry  of  both  inorganic  and  organic  substances  ad- 
vanced with  great  rapidity  during  the  nineteenth  century,  and 
among  the  facts  which  were  established  was  the  widespread  oc- 
currence of  proteins,  carbohydrates  and  fats  as  components  of 
foods,  thus  disproving  the  view  that  there  was  but  "one  kind  of 
aliment."  Of  these  nutrient  principles  only  the  first  named  con- 
tains the  element  nitrogen.  It  is  the  oxidation  of  these  food  sub- 
stances that  yields  the  energy  which  keep  the  body  warm,  and 
enables  it  to  do  mechanical  work.  The  laws  governing  energy 
metabolism  were  next  developed. 

44.  Lavoisier  Placed  Nutrition  on  a  Scientific  Foundation. 
— The  modern  era  of  the  science  of  nutrition  may  be  said  to  have 
been  introduced  by  the  famous  French  scientist,  Lavoisier,  in 
1780.  He  was  the  first  to  apply  the  thermometer  and  the  bal- 
ance to  the  study  of  the  chemical  changes  taking  place  in  the 
living  body.  He  established  the  fundamental  fact  that  the  pro- 
duction of  heat  involved  the  combination  of  the  oxygen  of  the  air 
with  the  substances  taken  into  the  body  as  food,  and  was  in  fact 
a  process  of  combustion.  He  discovered  that  the  temperature 
of  the  air  had  a  pronounced  influence  on  the  rate  at  which  sub- 
stances in  the  body  were  oxidized.  It  is  slow  at  temperatures 
which  we  find  comfortable  with  light  clothing,  and  is  greatly 
accelerated  by  cold.  Exercise,  he  found  to  stimulate  combustion 
in  the  body,  and  he  also  observed  that  during  work  it  might  rise 
to  several  times  the  resting  metabolism.  These  fundamental 
facts  established  by  Lavoisier  have  formed  the  subjects  of  nu- 
merous investigations,  which  greatly  increased  our  knowledge  of 
detail  in  this  important  field. 

About  1842  Joule  described  experimental  data  establishing  the 
mechanical  equivalent  of  heat.  Heat  is  measured  in  terms  of 
the  calorie,  which  is  the  amount  of  heat  necessary  to  raise  the 
temperature  of  1  cubic  centimeter  of  water  1  degree  centigrade, 
or  one  pound  of  water  4  degrees  Fahrenheit.  Another  unit,  the 
large  Calorie,  is  1,000  times  the  small  calorie.  The  rate  at  which 
energy  metabolism  varies  with  the  activity  of  the  individual,  and 
in  the  absence  of  suitable  clothing,  with  the  temperature,  is  the 
most  spectacular  phase  of  the  metabolic  processes,  and  is  easily 
observed.  A  man  at  rest  may  have  need  of  only  about  1,600 
calories  a  day  in  the  form  of  suitable  food,  in  order  to  cover  his 


42       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

energy  requirements.  The  same  man  at  very  severe  labor  may 
require  10,000  calories  a  day.  It  is  not  surprising  that  this  ob- 
viously important  phase  of  metabolism  was  early  studied  in  great 
detail. 

In  1866,  Pettenkofer  and  Voit  in  the  University  of  Munich, 
began  the  publication  of  their  elaborate  studies  on  energy  metab- 
olism carried  out  with  the  aid  of  a  respiration  apparatus  by 
means  of  which  they  could  measure  accurately  the  amount  of 
oxygen  absorbed,  the  amount  of  carbon  dioxid  and  of  water  in 
the  products  of  respiration  and  the  heat  given  off  by  the  body 
under  various  conditions  (2).  They  introduced  into  their  ex- 
perimental work  the  idea  suggested  by  Liebig  in  1842,  that  the 
nitrogen  eliminated  in  the  urine  could  be  made  a  measure  of  the 
amount  of  protein  destroyed  in  metabolism,  since  protein  is  the 
one  prominent  food-stuff  which  contains  this  element.  Petten- 
kofer and  Voit  studied  the  metabolism  of  fasting  men  and  dogs, 
and  of  the  same  subjects  when  taking  different  kinds  and 
amounts  of  food.  From  the  magnitude  of  the  "respiratory  quo- 
tient," which  is  the  figure  obtained  by  dividing  the  volume  of 
carbon  dioxid  eliminated  by  the  volume  of  oxygen  consumed  in 

CO 

respiration  (-f^)  >  it  was  possible  to  decide  what  kind  of  food  was 

O2 

being  oxidized  as  a  source  of  energy  in  the  body.  When  car- 
bohydrate is  burned  the  quotient  is  1.  When  fat  is  burned  it  is 
0.7,  and  when  protein  is  burned  the  figure  is  approximately  0.8. 
They  found  that  a  dog  could  be  maintained  in  nitrogen  and 
energy  equilibrium  during  a  period  of  a  few  days  on  a  diet  of 
protein  alone  (muscle  tissue).* 

45.  The  Specific  Dynamic  Action  of  Food-Stuffs. — The 
early  studies  relating  to  energy  metabolism  led  to  the  discovery 
that  the  protein  of  the  food  differs  in  one  marked  respect  from 
either  carbohydrate  or  fat,  by  its  great  stimulating  effect  upon 
metabolic  processes  as  measured  by  the  rate  of  oxidation.  This 
is  illustrated  by  the  following  type  of  experiment:  If  a  dog  is 
observed  when  it  has  been  for  some  hours  without  food,  and  the 
rate  of  energy  metabolism  carefully  measured,  it  will  be  found 
that  this  remains  constant  within  narrow  limits  so  long  as  the 
animal  remains  at  rest.  If  now  it  is  fed  liberally  with  either 
fat  or  carbohydrate  and  the  observations  on  its  energy  metab- 

*  For  a  detailed  history  of  this  important  phase  of  nutrition,  the  reader 
is  referred  to  "The  Science  of  Nutrition,"  Graham  Lusk,  3d  Ed.  Phila- 
delphia, 1917. 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS      43 

olism  are  continued,  there  is  observed  a  slight  increase  in  metab- 
olism which  is  the  direct  result  of  the  utilization  of  these  foods. 
If  on  the  other  hand,  a  liberal  portion  of  protein  rich  food,  such 
as  meat  is  fed  to  the  animal  instead  of  the  non-nitrogenous  nutri- 
ents, there  is  a  surprising  acceleration  of  the  metabolic  processes, 
attended  with  a  marked  increase  in  energy  set  free  within  the 
tissues.  This  was  first  shown  by  Bidder  and  Schmidt  in  1852. 
Their  experimental  animal  was  a  cat.  During  a  certain  interval 
of  time  the  animal  used  50.18  grams  of  oxygen  and  eliminated 
from  its  lungs  53.52  grams  of  carbon  dioxid.  The  animal  was 
then  allowed  to  eat  all  the  meat  it  would  consume  and  the  ob- 
servations continued.  During  a  similar  interval  the  cat  used 
103.84  grams  of  oxygen  and  respired  113.52  grams  of  carbon 
dioxid  (3). 

46.  Energy  and  Protein  Were  Long  Regarded  as  the  Most 
Important  Factors  in  Nutrition. — The  remarkable  researches  of 
Voit,  Pettenkofer,  Rubner,  Atwater,  Lusk,  Zuntz  and  Benedict  on 
the  metabolism  of  matter  and  energy  in  the  body  attracted  de- 
served attention  and  for  years  occupied  a  large  area  in  the  field 
of  vision  of  students  of  nutrition.  The  researches  were  extended 
to  the  study  of  some  of  the  finer  problems  of  metabolism.  It  was 
shown  that  carbohydrate  can  be  converted  into  fat  by  the  tissues, 
and  that  a  part  of  the  carbon  which  the  protein  molecule  con- 
tains can  be  converted  in  the  body  into  glucose.  These  investi- 
gations shed  much  light  on  such  conditions  of  perverted  metab- 
olism as  prevent  the  oxidation  of  sugar  in  the  tissues  (diabetes). 
In  the  light  of  the  new  developments  in  the  chemistry  of  pro- 
teins and  their  digestion  products,  the  amino-acids,  Lusk  finally 
explained  in  great  measure,  the  cause  of  the  specific  dynamic 
action  of  proteins  (4). 

It  was  not  until  after  1900  that  the  view  began  to  develop  that 
differences  in  chemical  composition  brought  forth  great  differ- 
ences in  the  nutritive  values  of  proteins  from  different  sources. 
Previous  to  that  time  it  was  believed  by  those  who  were  inter- 
ested in  the  nutrition  of  man  and  animals,  that  the  results  of  a 
chemical  analysis  were  of  the  greatest  importance  in  showing 
the  nutritive  value  of  any  food,  and  on  the  basis  of  such  analysis, 
advice  was  given  as  to  the  manner  in  which  foods  should  be  com- 
bined. The  chemical  methods  in  use  at  that  time  were  first 
described  in  1864  by  Henneberg,  and  were  adopted  by  the  Ger- 
man Official  Agricultural  Chemists,  and  afterwards  used  by  food 
chemists  all  over  the  world. 


44       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

47.  What  a  Food  Analysis  Is  Intended  to  Show. — The  food 
analysis  consisted  in  the  following  determinations:  The  nitrogen 
content,  from  which  the  protein  was  calculated  by  multiplying 
the  value  found  by  6.25,  on  the  assumption  that  all  proteins  con- 
tained approximately  16  per  cent  of  nitrogen;  the  fat,  by  ex- 
tracting the  food  with  some  solvent,  usually  ether,  and  weighing 
the  amount  of  substance  which  was  extracted  from  a  known 
amount  of  food;  the  "crude  fiber,"  or  cellulose,  by  treating  a 
sample  of  the  food  with  a  solution  of  acid  and  then  with  one  of 
alkali  sufficiently  strong  to  dissolve  all  components  except  the 
more  resistant  forms  of  cellulose,  and  a  small  amount  of  mineral 
matter  which  this  cellulose  retained;  the  ash,  or  mineral  matter, 
by  burning  a  weighed  sample  and  subsequently  weighing  the 
residue  left  after  incineration.    The  analysis  was  made  on  a 
sample  of  food  which  was  carefully  dried  to  constant  weight  in 
order  to  free  it  from  moisture.    The  sum  of  the  protein,  fat,  ash 
and  fiber,  was  then  subtracted  from  100  to  give  a  figure  which 
was  designated  "nitrogen-free  extract."    This  was  assumed  in 
calculations  used  in  estimating  the  amount  of  food  necessary  to 
meet  the  requirements  of  an  individual  as  being  essentially  a 
measure  of  the  amount  of  utilizable  carbohydrate  contained  in 
the  food.    Such  in  outline  is  the  chemical  analysis  of  a  food. 
It  will  be  seen  later  that  the  biological  method  of  analysis  is 
very  essential  to  complete  our  knowledge  of  the  nutritive  value 
of  foods. 

By  1900  very  careful  determinations  had  been  made  of  the 
amount  of  heat  liberated  when  a  definite  weight  of  the  food  is 
burned.  This  was  known  as  the  calorific  or  fuel  value.  Nu- 
merous determinations  had  been  made  of  the  amount  of  energy 
required  for  a  man  of  ordinary  size,  per  day,  when  at  rest  and 
when  doing  several  kinds  of  work  representative  of  moderate  and 
more  severe  kinds  of  labor.  The  illustration  most  widely  used 
by  writers  on  nutrition,  was  that  of  comparing  the  body  to  an 
engine,  in  which  fuel  (food)  was  burned  and  by  which  mechani- 
cal work  was  performed,  with  the  liberation  of  a  certain  amount 
of  waste  energy  in  the  form  of  heat.  The  adjustment  of  the 
supply  of  calories,  or  energy  units  of  food,  to  the  needs  of  the 
individual,  and  the  amount  of  protein  necessary  to  make  good 
the  "wear  and  tear"  of  the  tissues,  which  is  an  unavoidable  re- 
sult of  the  life  processes,  were  considered  as  the  two  factors  of 
prime  importance  in  the  planning  of  the  diet. 

48.  Elements  of  Weakness  in  the  Standard  Food  Analysis. 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS     45 

— The  standard  food  analysis  regarded  of  so  great  importance, 
had  a  number  of  shortcomings,  as  a  method  of  determining  the 
nutritive  value  of  a  food.  By  means  of  it  the  great  differences 
in  the  make-up  of  the  proteins,  which  give  them  very  unlike 
value  in  nutrition,  were  not  revealed.  Protein  from  one  source 
was  assumed  to  be  as  good  as  that  from  another.  Beans  and 
peas,  for  example,  contain  about  23  per  cent  of  protein,  and  com- 
pare favorably  in  this  constituent  with  lean  meat.  These  legume 
seeds  were  regarded  for  many  years  as  essentially  the  equivalent 
of  meat  as  a  source  of  protein.  They  were  sometimes  spoken 
of  as  "the  poor  man's  meat."  We  now  know  that  the  proteins 
of  these  seeds  have  peculiarities  in  their  composition  which 
make  them  of  relatively  low  value  in  nutrition  when  they  serve 
as  the  sole  source  of  protein  in  the  diet,  or  when  they  are  com- 
bined with  some  of  our  most  important  food  grains.  Meat 
proteins  are  decidedly  superior  to  them  as  supplements  to  most 
of  the  proteins  of  our  vegetable  foods.  This  was  only  brought 
to  light  by  later  investigations. 

The  analysis  of  foods  for  their  carbohydrate  content  was  not 
effective  as  a  means  of  arriving  at  a  decision  as  to  the  energy 
value  of  this  portion  of  their  substance.  Man  and  animals  can 
use  starch  and  sugars  as  a  source  of  energy,  but  not  cellulose  or 
hemicelluloses.  The  best  method  for  differentiating  between  the 
several  types  or  carbohydrates  was  that  based  on  the  ease  with 
which  they  are  converted  into  glucose  or  other  simple  sugars  by 
the  action  of  acid  of  certain  concentration.  The  true  celluloses, 
of  which  paper  is  made,  are  not  dissolved  by  the  reagents  used  in 
food  analysis,  and  could  be  filtered  off,  washed,  dried  and 
weighed.  There  are  many  kinds  of  vegetable  foods  which  con- 
tain considerable  amounts  of  hemicelluloses,  a  class  of  carbo- 
hydrates which  are  easily  converted  by  the  action  of  acid  into 
simple,  soluble  sugars  in  the  process  of  analysis.  Accordingly, 
these  were  estimated  as  part  of  the  fraction  called  "nitrogen- free 
extract,"  and  were,  in  the  absence  of  specific  data  as  to  their 
digestibility,  estimated  in  calculations  of  dietaries,  as  the  equiva- 
lent of  starch  or  sugar. 

Hemicelluloses  are  not  acted  upon  by  the  digestive  secretions 
of  man  or  animals.  They  have,  therefore,  no  food  value  except 
that  imparted  to  them  through  the  agency  of  certain  microorgan- 
isms inhabiting  the  digestive  tract.  These  organisms  may  bring 
about  their  fermentation  with  the  production  of  such  organic 
substances  as  acids  and  alcohols  as  intermediary  products.  These 


46       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

may  be  absorbed  and  utilized  by  the  body  as  a  source  of  energy 
for  mechanical  work  or  for  heat  production. 

The  method  for  the  estimation  of  fat  in  food-stuffs  was  fairly 
satisfactory,  but  the  materials  weighed  as  fat  always  contain 
waxes,  cholesterol,  chlorophyll,  etc.  These,  with  the  possible  ex- 
ception of  chlorophyll,  have  no  food  value,  and  are  inert  and 
chance  components  of  the  diet.  The  fats  and  carbohydrates 
were  regarded  as  essentially  sources  of  energy  for  work  or  for 
heat  production,  and  were  rightly  considered  as  being  able  to 
replace  each  other  in  the  diet  in  isodynamic  quantities.  One 
gram  of  carbohydrate  or  of  protein  has  a  caloric  value  of  about 
4.1,  while  1  gram  of  fat  has  about  twice  this  fuel  value. 

The  mineral  content  of  a  food-stuff  was  determined  in  the 
standard  method  of  analysis  by  burning  a  weighed  sample  in  a 
dish  of  known  weight.  After  the  organic  matter  was  all  de- 
stroyed, the  dish  was  cooled  in  a  dry  atmosphere  and  reweighed. 
The  difference  between  the  weight  of  the  dish  and  the  dish  plus 
the  ash  gave  the  weight  of  the  mineral  matter.  Little  signifi- 
cance was  attached  to  the  inorganic  content  of  foods  until  recent 
years,  for  it  was  assumed  that,  since  all  the  elements  which  are 
required  by  the  body  are  found  in  all  foods,  the  amounts  might 
vary  considerably  and  still  meet  the  needs  of  the  body.  In  spe- 
cial cases  the  deficiency  of  a  food  in  a  particular  element  was  so 
pronounced  that  it  attracted  attention.  Thus  milk  is  especially 
poor  in  iron,  and  since  this  element  is  a  constituent  of  the  hemo- 
globin of  the  blood,  it  was  early  recognized  that  a  young  child 
should  not  be  too  long  confined  to  an  exclusive  milk  diet,  but 
should  be  given  some  food  which  would  supplement  milk  in  this 
respect. 

49.  Proportions  Among  the  Mineral  Elements  in  Food 
Long  Regarded  as  of  Little  Significance. — It  was  not  possible 
to  determine  the  adequacy  of  the  content  of  our  common  foods 
in  any  of  the  inorganic  elements  until  exact  studies  had  been 
made  to  determine  the  efficiency  of  the  animal  body  in  absorbing 
and  in  conserving  its  supply.  The  variations  in  the  inorganic 
content  of  the  blood  in  health  and  disease  are  so  small  as  to 
escape  observation  by  any  but  the  most  modern  and  refined 
methods.  Yet  these  variations  are  of  great  significance  to  the 
welfare  of  the  individual.  Unwarranted  assumptions  were  made 
by  the  earlier  students  of  nutrition,  concerning  the  ability  of  the 
intestines  to  absorb  mineral  salts  in  a  selective  way  so  as  to  lead 
to  the  utilization  with  high  efficiency  those  elements  present  in 
the  food  in  small  amounts.  The  capacity  of  the  kidney  to  hold 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS     47 

back  those  elements  which  are  present  in  the  food  in  minimal 
amounts  and  therefore  reach  the  blood  in  amounts  below  the 
optimum  was  over  rated.  It  is  now  known  that  the  efficiency  of 
the  kidneys  in  preventing  the  passage  of  inorganic  salts  into  the 
urine  along  with  the  waste  products  of  metabolism,  is  not  so 
great  as  to  protect  the  body  from  losses  which  may  be  injurious 
to  it  when  the  food  contains  as  little  of  such  salts  as  those  of 
calcium,  phosphorus,  sodium  and  chlorin  as  are  contained  in 
some  of  our  most  important  cereal  grains,  tubers  and  meats. 
There  are  well  defined  limits  to  the  degree  to  which  the  intake 
of  these  salts  can  be  restricted  without  causing  damage. 

50.  The  Objective  of  Students  of  Digestion. — It  was  fully 
appreciated  by  students  of  nutrition  many  years  ago  that  the 
food  analysis  had  its  serious  limitations,  and  the  belief  prevailed 
that  the  way  to  eliminate  the  defects  of  chemical  technic,  was  to 
supplement  the  data  obtained  by  chemical  methods  with  infor- 
mation secured  by  actual  trials  to  determine  the  digestibility  of 
foods.  The  subject  and  the  diet  having  been  decided  upon,  sam- 
ples of  the  food  to  be  eaten  were  carefully  analyzed  to  determine 
their  content  of  protein,  fat,  ash,  moisture  and  "nitrogen-free 
extract."  The  period  of  the  experimental  trial  varied  consider- 
ably, but  in  most  cases  it  covered  three  days.  It  was  customary 
to  keep  the  subject  on  a  milk  diet  during  a  fore  period,  so  that 
the  feces  derived  from  the  experimental  diet  would  be  different 
in  appearance  and  could  be  accurately  separated.  The  chemical 
constituents  of  the  ingested  food  minus  the  amounts  of  each 
which  appeared  in  the  fecal  residues,  afforded  the  data  from 
which  the  digestibility  of  the  protein,  fat  and  carbohydrate  were 
calculated. 

There  were  some  errors  in  this  procedure.  In  addition  to  the 
food  substances  which  escaped  digestion,  a  part  of  the  nitrogen 
and  salts  eliminated  from  the  intestine  were  derived  from  the 
secretions  of  the  digestive  glands,  and  from  the  cellular  elements 
which  came  from  the  intestinal  mucosa.  The  quantity  of  secre- 
tions eliminated  from  the  tract  depended  in  great  measure  on  the 
content  of  indigestible  cellulose  in  the  food.  This  acted  as  a 
sponge,  and  retained  liquids  so  that  they  could  not  be  reabsorbed. 
An  animal  which  is  fed  a  diet  containing  just  sufficient  protein  to 
meet  its  needs,  may  easily  be  made  to  suffer  a  nitrogen  deficit 
by  including  in  its  food  supply  a  liberal  amount  of  cellulose  or 
other  indigestible  carbohydrate  such  as  are  abundant  in  many 
vegetables. 

In  interpreting  the  results  of  digestion  experiments  "utiliza- 


48       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

tion"  of  the  several  components  of  the  food  was  assumed  to  be 
measured  by  the  extent  to  which  they  disappeared  from  the  diges- 
tive tract.  That  such  an  interpretation  is  not  always  justified  is 
readily  understood.  A  diet  of  cereal  grains  will  be  well  digested 
and  absorbed,  but  the  substances  which  reach  the  blood  and  tis- 
sues are  not  a  satisfactory  pabulum  for  the  nutrition  of  the  body. 
Some  complexes  which  are  indispensable  to  the  body  are  present 
in  too  small  amounts  to  admit  of  the  utilization  of  the  other  use- 
ful ones  which  are  abundant,  but  cannot  serve  a  useful  purpose 
unless  they  can  be  used  to  form  definite  structures,  no  unit  of 
which  can  be  dispensed  with.  Such  a  food  supply  may  be  well 
absorbed  but  not  assimilated.  Utilization  is  an  unfortunate 
choice  of  a  term  in  this  sense  for  it  is  liable  to  be  misinterpreted. 
Knowledge  of  the  digestibility  of  food-stuffs  is  of  value  to  stu- 
dents of  nutrition,  but  the  idea  of  quality  in  the  array  of  diges- 
tion products  must  not  be  lost  sight  of. 

51.  Limitations  of  Value  of   Chemical   Composition  and 
Digestibility  of  Foods. — It  will  be  appreciated  in  the  light  of 
what  has  been  said  that  the  chemical  analysis  of  a  food,  and 
knowledge  concerning  its  digestibility,  even  when  its  palatability 
is  satisfactory,  do  not  give  any  information  concerning  its  physi- 
ological effects.    These  can  be  discovered  only  by  observations  on 
the  well-being  of  men  or  animals  restricted  during  considerable 
periods  of  time  to  a  definite  type  of  diet.    It  was  for  a  long  time 
assumed,  and  without  any  experimental  evidence  in  support  of 
the  assumption,  that  any  diet  which  complied  with  the  com- 
position   of    ordinary    combinations    of    foods,    which    experi- 
ence had  shown  to  be  palatable  and  wholesome  components  of  the 
diet,  and  was  so  constituted  as  to  furnish  the  necessary  amount 
of  protein  and  of  energy  in  digestible  form,  would  promote  growth 
and  prolonged  well-being  if  available  in  sufficient  quantities. 
This  popular  conception  we  now  know  to  be  far  from  true. 

52.  The  Study  of  Supplementary  Foods  in  Animal  Produc- 
tion.—It  gradually  became  the  custom  in  Agricultural  Experiment 
Stations  to  compare  the  effects  of  certain  combinations  of  foods 
on  the  growth  of  young  animals,  and  on  milk  production  in 
cows.    These  experiments  showed  plainly  that  all  rations  of 
similar  chemical  composition  are  not  alike  in  their  physiological 
effects.    In  no  instance  was  it  possible,  however,  because  of  lack 
of  knowledge  of  the  several  factors  which  enter  into  the  normal 
diet,  and  because  of  the  faulty  planning  and  conduct  of  many 
of  the  experiments,  to  interpret  the  nature  of  the  causes  which 
determined  their  outcome.    These  belonged  to  the  type  of  im- 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS      49 

mediate  utility  experiment  and  were  fostered  by  agricultural  ex- 
periment stations  because  of  their  practical  nature.  They  were 
of  very  great  economic  value  since  they  showed  clearly  that  cer- 
tain combinations  of  foods  were  either  poor,  good  or  excellent  for 
the  nutrition  of  animals.  The  experiments  were  not,  because  of 
the  nature  of  the  food-stuffs  employed,  and  because  of  the  simple 
mixtures  which  were  monotonously  fed  to  the  animals,  of  such  a 
nature  as  to  make  possible  deductions  applicable  to  problems 
of  human  nutrition.  Much  of  this  experimental  work  was  done 
by  men  with  little  scientific  training.  The  experiments  were 
therefore  very  poorly  controlled  with  the  result  that  much  con- 
fusion prevailed.  Instances  were  not  infrequent  where  the  title 
of  a  paper  would  lead  one  to  believe  that  the  experiments  were 
designed  to  determine  the  efficiency  with  which  a  certain  protein- 
rich  concentrate  supplements  each  of  several  cereal  foods  in  the 
nutrition  of  growing  swine,  but  a  careful  inspection  would  show 
that  the  ration  described  was  fed  to  animals  allowed  to  run  on  a 
pasture,  and  eating  freely  of  a  forage  plant,  or  given  such  a  skim 
milk  supply  as  the  dairy  department  afforded.  But  no  account 
was  taken  of  these  factors  in  the  interpretation  of  the  results. 

53.  The  Conception  of  Specific  Effects  of  Different  Nutri- 
ents.— In  1900  nutrition  studies  made  for  the  purpose  of  solving 
the  problems  of  economic  animal  production  had  developed  the 
conception  of  the  specific  effects  of  different  foods  on  the  develop- 
ment of  the  body  during  growth,  and  for  the  performance  of  work 
or  the  production  of  milk,  wool,  etc.    The  skilled  animal  hus- 
bandryman  was  distinctly  in  advance  of  the  human  physiologist 
or  the  medical  man  in  his  knowledge  of  nutrition  from  the  prac- 
tical standpoint.    Professor  Atwater,  who  represented  the  most 
advanced  thought  of  his  time,  wrote,  in  1895,  his  "Chemistry 
and  Economy  of  Food"  (5),  which  clearly  reflects  his  view  that 
if  we  knew  the  composition  of  all  the  food-stuffs  entering  into 
the  human  diet,  as  determined  by  chemical  analysis,  their  digesti- 
bility, and  energy  values,  and  the  energy  requirements  of  an 
individual  at  rest  and  when  doing  various  kinds  of  work,  we 
should  have  all  the  necessary  data  to  enable  us  to  plan  a  highly 
satisfactory  nutritive  regimen.    The  well-balanced  diet  was  one 
in  which  the  proportions  among  the  several  recognized  nutrients 
corresponded  with  the  standards  adopted  as  the  result  of  statis- 
tical studies  of  what  people  in  different  circumstances  and  in 
different  localities  were  selecting  for  their  food  supply  when 
guided  by  the  appetite  and  by  expenditure. 

54.  Efforts  to   Study   Food   Requirements  by   Statistical 


50       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Methods. — These  dietary  studies  were  all  made  after  the  plan 
introduced  by  Voit  in  Germany.  Atwater  made  numerous 
studies  of  American  dietaries,  including  the  homes  of  laborers, 
professional  men,  students  and  others.  Much  interest  was  mani- 
fested by  the  public  in  these  results  and  others  took  up  similar 
investigations  so  that  we  have  available  the  diets  of  people  in 
all  parts  of  the  country  and  in  all  walks  of  life  during  the  period 
from  1890  to  1900.  The  diets  of  Alabama  negroes,  Mexican 
laborers  in  New  Mexico,  students  in  boarding  clubs,  families  of 
faculty  members  in  several  universities,  Maine  lumbermen,  for- 
eign families  of  various  nationality  as  well  as  workingmen's  and 
professional  men's  households  were  subjected  to  scientific  scru- 
tiny. The  quality  of  any  dietary  was  evaluated  by  comparison 
with  the  standards  adopted  by  Atwater  and  Voit  for  energy  and 
protein.  This  great  body  of  studies  were  for  the  most  part  pub- 
lished in  bulletins  of  the  United  States  Department  of  Agricul- 
ture. Their  collection  represents  an  epoch  in  the  development  of 
knowledge  of  human  nutrition. 

55.  A  Mistaken  Idea  Regarding  Economy  in  the  Purchase 
of  Foods. — When  our  knowledge  of  nutrition  had  advanced  to 
this  point  it  was  natural  that  the  idea  of  economy  in  food  should 
attract  a  great  deal  of  attention,  because  on  the  average,  a  half 
or  more  of  the  family  income  is  spent  for  food.  In  the  household 
of  a  wage-earner  food  is  the  largest  single  item  in  the  family 
budget.  Dr.  Atwater  made  some  calculations  concerning  the 
amounts  of  protein,  fat,  carbohydrates  and  fuel  values  which 
could  be  purchased  for  twenty-five  cents.  These  results  made  it 
clear  that  at  that  time  (1884)  this  sum  in  Massachusetts  would 
buy  one-sixth  of  a  pound  of  protein,  one-fifth  of  a  pound  of  fat, 
and  1,120  calories  of  energy  if  expended  for  sirloin  steak.  The 
same  amount  spent  for  oysters  at  50  cents  a  quart  purchased  one 
ounce  of  protein,  two  ounces  of  total  nutrients  and  230  calories  of 
energy.  In  buying  wheat  flour  at  seven  dollars  a  barrel  the 
twenty-five  cents  would  pay  for  six  and  a  quarter  pounds  of 
nutrients  containing  eight-tenths  of  a  pound  of  protein  and 
11,755  calories  of  energy.  Since  it  was  accepted  that  the  quality 
of  each  of  the  nutrients  from  each  of  these  foods  common  in  the 
American  diet,  was  essentially  the  same,  the  logical  course  seemed 
to  be  to  buy  the  cheaper  articles  when  economy  was  essential. 
There  was  no  fear  that  any  diet  would  prove  unsatisfactory  pro- 
vided it  contained  sufficient  protein  and  sufficient  available 
energy. 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS      51 

It  was  pointed  out  by  Atwater  that  the  price  of  food  was  not 
regulated  solely  by  its  nutritive  value,  but  that  agreeatileness  to 
the  palate  or  to  the  fancy  was  a  factor  of  great  significance  in 
determining  the  market  price.  There  was  at  that  time,  and  even 
after  the  year  1900,  no  appreciation  of  the  peculiar  worth  of 
certain  foods  as  supplements  to  others.  Nor  was  there  any 
appreciation  of  the  differences  in  quality  of  foods  such  as  we  now 
fully  recognize.  The  astonishing  fact  that  certain  lists  of  com- 
mon foods  do  not  maintain  satisfactory  nutrition  even  though 
they  have  collectively  a  chemical  composition  exactly  similar  to 
those  of  another  list  which  is  satisfactory  for  the' promotion  of 
nutritive  well-being  did  not  become  appreciated  until  about  1915. 

56.  The  Idea  of  Physiological  Economy  in  Nutrition. — It 
is  the  great  merit  of  Professor  .Chittenden  of  Yale  University  to 
have  introduced  into  nutrition  studies  the  idea  of  physiological 
economy  in  nutrition  (6).  Numerous  dietary  studies  in  Europe 
and  America  had  shown  fairly  accurately  what  the  people  in 
several  countries  were  eating,  and  the  amounts  and  the  chemical 
composition  of  the  foods  had  been  carefully  determined.  The 
most  notable  students  of  this  subject  were  Voit  in  Munich,  and 
Atwater  in  America.  Voit  came  to  the  conclusion  that  an  adult 
man  weighing  70-75  kilos  and  doing  moderate  work  requires  118 
grams  of  protein  daily,  56  grams  of  fat  and  500  grams  of  carbo- 
hydrate, the  diet  furnishing  3,000  calories  of  energy.  Atwater's 
standard  called  for  120  grams  of  protein.  These  standards  were 
based  upon  statistical  studies  of  large  numbers  of  people.  It 
was  assumed  that  appetite  and  instinct  were  safe  guides  to  the 
physiological  needs  of  the  body. 

These  standards  were  arrived  at  through  studies  of  the  actual 
consumption  of  food  by  families  in  various  walks  of  life.  Those 
who  accepted  them  as  the  amounts  of  the  various  food  com- 
ponents which  the  body  requires  under  specified  conditions,  ac- 
cepted the  view  that  man,  when  in  a  position  to  select  his  food 
from  a  suitable  variety  such  as  exists  in  times  of  relative  plenty 
and  moderate  values,  would  take  under  the  guidance  of  the 
appetite  such  amounts  of  food  as  are  best  suited  to  his  bodily 
needs.  Dr.  Chittenden  was  the  first  to  seriously  question  this 
doctrine  of  instinctive  selection.  He  applied  what  ssemed  at 
the  time  to  be  a  crucial  test  for  the  trustworthiness  of  this  doc- 
trine. He  restricted  men  over  a  period  of  nine  months  to  diets, 
the  protein  content  of  which  fell  far  below  the  amount  which 
physiologists  generally  had  accepted  as  the  actual  need. 


52       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Dr.  Chittenden  began  cautiously  experimenting  on  himself  to 
discover  how  low  he  could  reduce  the  protein  in  his  diet  without 
interfering  with  his  well-being,  and  to  his  surprise  he  remained 
in  nitrogen  equilibrium  and  in  improved  physical  condition  on  a 
diet  which  contained  only  sufficient  nitrogen  of  a  digestible  and 
absorbable  nature  to  make  the  nitrogen  content  of  the  urine 
average  5.699  grams  daily  over  a  period  of  nearly  nine  months. 
This  corresponds  to  about  36.72  grams  of  digestible  protein.  Dr. 
Chittenden  felt  convinced  that  this  reduction  of  the  intake  of 
protein  to  approximately  one-third  of  the  accepted  standard  re- 
quirement for  the  human  body  resulted  in  marked  improvement 
in  physiological  well-being.  He  determined  to  test  this  ques- 
tion on  a  scale  which  would  afford  convincing  evidence,  in  order 
that  mankind  might  profit  by  what  was  believed  to  be  a  great 
discovery,  that  physiological  economy  in  nutrition  is  a  matter 
of  great  importance  for  the  maintenance  of  strength  and  vigor. 

57.  The  Basis  of  Chittenden's  Views. — The  reasoning  by 
means  of  which  the  good  results  of  this  abstemious  diet,  and 
especially  of  the  low  protein  intake,  were  accounted  for  is  in- 
teresting indeed.  A  diminished  intake  of  protein  leads  to  a 
decreased  formation  of  crystalline  waste  products,  such  as  acid 
potassium  phosphate,  uric  acid  and  the  purin  bases  and  other 
end-products  of  nitrogen  metabolism.  These  are  in  part  respon- 
sible for  the  sensation  of  fatigue  when  they  accumulate  in  the 
blood.  The  energy  of  work  comes  not  from  the  degradation  of 
muscle  substance,  but  from  the  combustion  of  non-nitrogenous 
food-stuffs  such  as  sugar  and  fat,  and  it  is  not,  therefore,  neces- 
sary to  take  large  amounts  of  protein  food  for  the  purpose  of 
replacing  the  wear  and  tear  quota,  for  the  latter  is  but  of  small 
magnitude  even  in  severe  work.  Protein  stimulates  body  metab- 
olism in  general,  and  hence  will  lead,  when  taken  in  excessive 
amounts,  to  a  rate  of  metabolism  far  in  excess  of  the  normal 
amount  which  results  from  a  diet  lower  in  this  factor.  This 
augmentation  in  the  metabolism  of  the  body  tissues  leads  to  a 
waste  of  energy-yielding  substances  which  might  otherwise  be 
conserved  for  useful  expenditure. 

It  was  noted  by  Dr.  Chittenden  that  while  on  the  low  protein 
diet  there  was  not  a  single  day  during  the  nine  months  when  his 
urine  was  turbid,  whereas  on  a  rich  protein  diet  it  was  necessary 
to  take  a  large  amount  of  water  in  order  to  prevent  the  kidneys 
from  becoming  clogged.  It  was  reasoned  that  this  low  protein 
regimen  should  relieve  the  kidneys  of  a  burden  and  would  tend 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS     53 

to  aid  them  in  maintaining  their  functional  capacity  unimpaired. 

In  order  to  demonstrate  in  a  large  way  the  importance  of  his 
flew  views,  Dr.  Chittenden  secured  the  cooperation  of  a  group 
of  his  colleagues  in  the  faculty  of  Yale  University  and  a  group 
of  volunteers  from  among  the  students.  These  men  were  allowed 
a  free  choice  of  food,  but  they  conscientiously  adhered  during  the 
period  of  the  experiment  to  the  regulations  which  were  imposed 
on  the  test.  A  group  of  soldiers  of  the  United  States  Army  was 
detailed  under  the  command  of  a  sergeant  to  participate  in  the 
experiment.  The  diet  afforded  to  these  men  was  similar  to  that 
taken  by  those  who  volunteered  to  subsist  on  a  diet  low  in  pro- 
tein and  of  a  somewhat  abstemious  character. 

In  the  case  of  the  faculty  and  student  groups  the  diet  chosen 
contained  but  little  or  no  meat,  and  this  automatically  tended  to 
lower  the  protein  intake  to  a  decidedly  low  level.  In  all  cases 
there  was  free  choice  of  food  in  these  two  groups. 

There  was  no  indication  that  the  men  who  participated  in  this 
experiment  were  not  in  excellent  physical  condition  at  the  end 
of  the  nine  months  during  which  they  were  nourished  on  an 
abstemious  although  somewhat  more  liberal  diet  both  in  energy 
and  protein  than  that  which  Dr.  Chittenden  had  himself  taken 
with  apparent  benefit.  The  conclusion  was  drawn  that  the  gen- 
eral standards  of  food  consumption  of  people  were  faulty.  The 
faults  in  the  ordinary  diet  lay  in  the  excessive  consumption  of 
food  and  especially  of  protein.  The  view  seemed  sustained  that 
the  body  is  better  nourished  when  the  amount  of  food  metabolized 
closely  corresponds  with  the  minimum  which  is  necessary  to 
cover  its  requirements.  This  better  nourishment  was  held  to  be 
due  to  the  relief  of  the  digestive  organs  and  the  organs  con- 
cerned with  the  transformation  of  protein  food,  especially  the 
liver,  as  well  as  the  organs  of  excretion,  the  kidneys  in  particular, 
from  an  excessive  burden  to  which  the  ordinary  eating  habits  of 
man  subject  them. 

There  can  be  no  doubt  that  the  diets  which  these  men  took 
did  not  lead  to  any  observable  deterioration  in  their  physical 
well-being.  All  practically  maintained  their  body  weights,  or  at 
least  lost  only  such  amounts  as  would  be  anticipated  as  the  re- 
sult of  the  physical  exercises  some  of  them  indulged  in  during 
the  test.  Their  strength  increased  during  the  experiment  where 
records  were  taken  and  all  were  said  by  their  observers  to  be  in 
a  normal  and  healthy  condition  at  the  end  of  the  experiment. 

58.     Crichton-Browne's  Views  on  Parsimony  in  Nutrition. 


54       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

— Chittenden's  conclusions  were  not  accepted  by  many  students 
of  human  nutrition.  A  critical  discussion  of  his  experimental 
data  and  conclusions  was  presented  by  Benedict  (7).  He  inter- 
preted the  digestion  data  obtained  with  the  soldiers  with  whom 
Chittenden  experimented,  as  indicating  that  the  low  protein  in- 
take had  influenced  adversely  the  absorption  of  protein  from 
the  alimentary  tract.  He  further  called  attention  to  the  fact 
that  animals  fed  low  protein  diets  do  not  thrive  so  well  as  on 
more  liberal  quantities.  Benedict  pointed  out,  as  did  Sir  James 
Crich ton-Browne,  that  dietary  studies  all  over  the  world  had 
shown  that  in  civilized  communities  where  productive  power, 
enterprise  and  civilization  are  at  their  highest,  man  has  instinc- 
tively and  independently  selected  liberal  rather  than  small  quan- 
tities of  protein  (8). 

It  should  be  stated  that  in  1917,  when  there  was  a  food  short- 
age brought  about  as  the  result  of  the  World  War,  Benedict 
conducted  an  experiment  on  twelve  men,  all  students  of  the 
Y.  M.  C.  A.  College  at  Springfield,  Mass.,  to  see  what  the  effects 
would  be  of  rapidly  reducing  the  body  weight  by  about  10  per 
cent  by  a  sharp  reduction  in  the  amount  of  food  ingested.  This 
was  accomplished  in  four  to  six  weeks.  Thereafter  the  food 
consumption  was  so  regulated  as  to  maintain  the  weight  at  the 
new  level.  Each  man  lost  approximately  150  grams  of  nitrogen, 
equivalent  to  about  a  kilogram  of  protein.  Their  metabolism 
was,  therefore,  reduced  to  a  distinctly  lower  level  than  normal 
during  the  greater  part  of  a  school  year.  From  the  results  of 
his  observations  he  was  led  to  modify  his  former  view  and  to 
become  a  convert  to  the  idea  that  the  abstemious  diet  best  pro- 
motes physical  well-being  (9). 

59.  Older  Experiments  Not  Satisfactorily  Planned  to  Give 
Results  of  a  Conclusive  Nature. — The  question  naturally  arises 
how  far  are  we  justified  in  drawing  conclusions  from  the  data 
furnished  by  these  experiments  on  the  point  of  whether  this  is 
a  satisfactory  regimen  to  which  man  may  safely  adhere  through- 
out the  adult  period  of  life.  It  must  be  admitted  that  in  the 
light  of  the  new  viewpoints  which  have  been  illuminated  by  ani- 
mal experimentation  during  the  past  decade,  these  results  on 
men  do  not  seem  sufficiently  convincing  to  warrant  any  conclu- 
sions relative  to  the  most  important  of  all  questions  which  arise 
in  the  life  of  the  individual,  that  of  maintaining  to  a  late  period 
in  life  the  full  vigor  of  youth. 

These  experiments  on  men  covered  approximately  1  per  cent 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS     55 

of  the  normal  span  of  life  for  individuals  of  their  age.  It  has 
been  abundantly  demonstrated  on  animals  that  diets  which  fall 
far  below  the  standard  of  quality  necessary  to  maintain  life 
and  vigor  over  a  very  great  fraction  of  the  span  of  life  of  which 
the  species  is  capable  of  living,  may  cause  no  noticeable  dete- 
rioration in  the  physical  condition,  during  even  5  per  cent  of 
the  normal  expectation  of  life.  In  order  to  produce  noticeable 
effects  by  faulty  diet  during  4  or  5  per  cent  of  the  average 
life,  it  is  necessary  that  the  faults  shall  be  relatively  severe.  Yet 
diets  which  are  just  good  enough  to  permit  a  young  animal  to 
develop  in  what  appears  to  be  an  approximately  normal  manner, 
may  cause  early  aging,  and  instability  of  the  nervous  system. 
Either  during  youth,  while  growth  is  still  in  progress,  or  after 
it  has  ceased,  the  adherence  for  even  brief  periods  of  a  few  days 
or  weeks  to  a  diet  which  is  unsatisfactory  in  some  degree,  leads 
to  a  deviation  from  the  normal  histological  structure  of  the  os- 
seous, the  nervous  or  the  circulatory  tissues,  depending  upon  the 
nature  and  extent  of  the  faults  in  the  food.  Such  abnormal 
modification  of  tissue  structure,  would  ordinarily  escape  observa- 
tion even  to-day,  and  certainly  a  few  years  ago. 

60.  Effects  of  Faulty  Diets  on  the  Life  History  of  Animals. 
— Let  us  illustrate  the  principle  we  have  in  mind  by  the  results 
of  animal  experimentation.  McCollum,  Simmonds  and  Parsons 
(10)  restricted  a  large  number  of  groups  of  young  rats  to  diets 
which  were  faulty  in  different  degrees  with  respect  to  the  quality 
of  their  protein  content.  The  experiments  included  the  period 
of  growth,  and  of  adult  life  at  least  to  the  point  of  marked  devel- 
opment of  senile  characters.  The  fertility  and  success  with  the 
nursing  of  young,  the  stability  or  instability  of  the  nervous  sys- 
tem as  shown  by  indifference  to  being  handled,  which  is  charac- 
teristic of  the  well-nourished  rat,  or  the  apprehensiveness  and 
timidity  of  the  malnourished  one,  were  carefully  observed,  etc. 
Successive  generations  of  the  same  families,  where  young  were 
reared,  were  maintained  on  the  family  diet.  These  experiments 
will  be  discussed  more  in  detail  in  a  later  chapter,  but  it  may  be 
stated  here  that  the  deviation  of  the  quality  of  the  protein 
moiety  of  the  diet  even  in  slight  degrees  from  the  optimum,  exerts 
a  profound  influence  on  the  life  history  of  the  animals  and  on  the 
functioning  of  the  nervous  system. 

It  may  be  added  that  the  faults  of  a  diet  need  be  no  more 
pronounced  than  are  encountered  in  a  mixture  consisting  of  cereal 
grains,  legume  seeds,  tubers,  fleshy  roots  and  muscle  meats,  to 


56       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

produce  profound  physical  deterioration  when  such  a  regimen 
is  adhered  to  over  any  considerable  period. 

61.  Longest  Experiments  on  Man  Have  Not  Exceeded  5 
Per  Cent  of  the  Possible  Life  Span. — The  Experiments  of 
Chittenden  and  of  Benedict  covered  but  approximately  1  per 
cent  of  the  expectation  of  life  of  the  young  men  who  served  as 
subjects.  They  can  scarcely  be  expected  to  be  used  as  a  basis  of 
deductions  of  a  far-reaching  nature  concerning  the  dietary  prac- 
tices which  man  may  safely  adhere  to  throughout  long  periods. 
Our  conclusions  as  to  what  is  safe  or  unsafe  must  be  arrived  at 
through  tests  of  special  types  of  diets  on  animals,  the  life  his- 
tories of  which  are  carefully  observed,  and  the  vitality  of  whose 
offspring  is  carefully  compared  with  a  satisfactory  standard  of 
excellence,  and  the  correlation  of  these  results  with  the  expe- 
rience of  man  in  various  parts  of  the  world,  where  groups  are 
found  whose  dietary  habits  are  of  peculiar  and  restricted  types. 
Such  data  will  be  set  forth  in  later  chapters  of  this  book. 

62.  "Optimal"  a  Better  Goal  Than  "Normal"  in  Planning 
the  Human  Diet. — The  studies  of  McCollum  and  Simmonds  have 
introduced  into  the  philosophy  of  nutrition  the  idea  that  the 
word  "normal"  is  too  indefinite  a  term,  and  less  satisfactory 
than  "optimal"  to  designate  the  standard  of  excellence  toward 
which  we  should  strive  in  respect  to  physical  development.  They 
emphasize  that  our  standards  of  what  constitutes  normality  are 
based  upon  common  observation  rather  than  upon  the  best  pos- 
sible achievement  as  illustrated  by  the  best  specimens  in  the 
population.  These  investigators  also  pointed  out  that  it  is  un- 
safe to  judge  by  the  appearance  or  feelings  of  a  man  or  animal 
under  special  conditions  during  a  relatively  small  fraction  of 
life,  especially  that  part  in  which  recuperative  power  and  en- 
durance are  greatest,  that  a  dietary  regimen  which  has  proven 
unsafe  for  the  promotion  of  vigor  and  health  in  animals,  is  safe 
for  man.  Physical  deterioration  may,  and  generally  is  un- 
noticed or  not  admitted  until  it  is  pronounced.  It  is  important 
to  appreciate  that  in  the  aggregate,  it  is  borderline  states  of 
malnutrition,  characterized  by  a  condition  of  nutritional  insta- 
bility, that  is  the  greatest  menace  to  the  individual  when  his 
health  and  efficiency  over  the  life  period  is  considered. 

With  this  attitude  toward  the  subject  of  our  discussion,  we 
may  now  turn  to  some  of  the  more  technical  phases  of  nutrition 
investigations,  the  results  of  which  have  served  as  a  basis  of 
practical  conclusions  of  great  value  for  the  health  of  man. 


THE  EARLIER  VIEWS  OF  NUTRITION  PROBLEMS      57 

BIBLIOGRAPHY 

1.  Myer,  J.  S.:    Life  and  Letters  of  William  Beaumont,  St.  Louis,  1912. 

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des  normalen  Menschen,  Zeit.  f.  Biol.,  1886,  ii,  537. 

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1852,  356.    Leipzig. 

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The  nutrition  of  man,  New  York,  1907. 

7.  Benedict,  F.  G.:    The  nutritive  requirements  of  the  body,  Amer.  Jour. 

of  Physiol.,  1906,  xvi,  409. 

8.  Crichton-Browne,  Sir  J.:     Parcimony  in  nutrition,  New  York,  1909. 

9.  Benedict,  F.  G.:     Physiological  effects  of  prolonged  reduction  in  the 

diet   of   twenty-five   men,   Trans.   Amer.   Philosophical   Soc.,    1918, 
Ivii,  479. 

10.  McCollum,  E.  V.,  Simmonds,  N.,  and  Parsons,  H.  T.:     Supplementary 
protein  values  in  foods,  Jour.  Biol.  Chem.,  1921,  xlvii,  111-247. 


CHAPTER  IV 

THE  NUTRITIVE  VALUE  OF  THE  PROTEINS  FROM 
VARIOUS  SOURCES 

63.  Protein  the  Mosit  Prominent  Organic  Component  of 
the  Body. — The  most  prominent  component  of  the  body  tissues, 
the  skeleton  excepted,  is  protein.  This  substance  is  the  basis 
of  the  muscles  and  glandular  tissues,  and  overshadows  all  other 
organic  compounds  in  relative  abundance.  Liebig  believed  that 
a  muscle  does  mechanical  work  at  the  expense  of  energy  stored 
in  it  in  the  form  of  protein.  The  energy  was  supposed  to  come 
from  the  change  of  the  complex  protein  molecule  into  simpler 
products,  analogous  to  the  change  of  complex  molecules  of  wood 
into  carbon  dioxid  and  water  during  combustion,  the  energy 
set  free  being  capable  of  appearing  in  part  in  the  form  of  work. 

If  this  view  were  correct,  the  amount  of  protein  which  is  broken 
down  daily  should  be  profoundly  influenced  by  the  amount  of 
work  performed.  Modern  investigations  have,  however,  estab- 
lished that  work  is  ordinarily  performed  at  the  expense  of  the 
energy  of  carbohydrates  such  as  starch  and  sugars  taken  in  the 
food,  or  from  fat.  This  was  first  shown  by  Pettenkofer  and 
Voit  (1)  in  1866.  These  investigators  observed  that  even  a 
fasting  man  showed  no  increased  protein  destruction  as  meas- 
ured by  the  amount  of  nitrogen  eliminated  in  the  form  of  waste 
end-products  in  the  urine.  Instead  of  prodigally  wasting  his 
muscle  substance  (protein)  he  burned  fat  as  a  source  of  energy. 
Recent  investigations  have  proven  that  following  severe  work 
there  is  an  increased  elimination  of  nitrogen  (1) . 

For  many  years  physiologists  assumed  that  the  tissues  of  the 
human  or  animal  organism  were  not  capable  of  synthetic  trans- 
formations so  as  to  give  rise  to  the  formation  of  complex  organic 
compounds  from  simple  ones.  The  building  up  of  organic  sub- 
stances from  inorganic  compounds  was  believed  to  occur  only  in 
plants  during  growth.  The  logical  inference  was  that  the 
wear  quota  of  the  protein-rich  tissues  must  be  replaced  by  new 
proteins  from  the  food.  Early  observations  on  fasting  men  and 
animals  established  the  fact  that  even  during  periods  of  ab- 

58 


NUTRITIVE  VALUE  OF  THE  PROTEINS  59 

stenance  from  food,  tissue  waste  still  goes  on,  and  in  the  ab- 
sence of  protein  in  the  diet  the  muscles  and  other  tissues  are 
used  up.  During  a  subsequent  period  of  feeding,  the  lost  muscle 
substance  may  be  completely  restored.  One  of  the  problems 
which  early  occurred  to  the  inquiring  mind  of  Carl  Voit  of 
Munich  (2)  was  that  of  determining  the  amount  of  protein  in 
the  form  of  meat,  which  would  suffice  to  prevent  a  nitrogen 
(protein)  deficit  in  dogs.  He  did  not  actually  determine  the 
minimum  amount  of  protein  necessary  to  accomplish  this,  but 
instead,  showed  that  with  moderately  large  intakes  of  meat 
protein,  the  nitrogen  which  appeared  in  the  urine  as  waste  prod- 
ucts of  metabolism,  plus  that  eliminated  in  the  feces,  was  equal 
to  that  ingested  in  the  food.  In  other  words  the  body  was  in 
nitrogen  (or  protein)  equilibrium. 

64.  Gelatin  is  an  "Incomplete"  Protein. — Gelatin,  which  re- 
sults from  incipient  hydrolysis  of  connective  tissue  and  the  or- 
ganic matrix  of  bone,  is  a  protein  of  peculiar  nature  which  early 
came  to  the  attention  of  chemists.  Gelatin  and  the  casein  of 
milk  were  among  the  proteins  first  to  be  separated  in  a  state  of 
approximate  purity.  Voit  attempted  to  substitute  with  gelatin 
a  part  or  all  of  the  meat  protein  in  the  diets  of  his  dogs  and 
discovered  that  gelatin  alone  as  the  sole  source  of  nitrogen  could 
not  prevent  loss  of  body  protein.  There  was  something  lacking 
in  its  makeup  which  made  it  an  incomplete  food.  Gelatin  be- 
came, therefore,  a  substance  of  unique  interest  to  physiological 
chemists. 

In  1849  Millon  (3)  discovered  a  reagent  which  when  added  to 
most  proteins  gives  a  characteristic  brick  red  color.  Gelatin 
does  not  exhibit  this  property.  In  1879  Nasse  (4)  demonstrated 
that  the  reaction  of  Millon  is  due  to  the  presence  in  the  protein 
molecule  of  the  amino-acid  tyrosin,  which  is  one  of  the  diges- 
tion products  of  many  proteins.  Gelatin,  therefore,  does  not 
yield  tyrosin  when  digested.  It  has  still  other  deficiencies 
which  were  later  discovered.  Tryptophan  and  the  sulphur-con- 
taining amino-acid,  cystin,  are  both  lacking  in  its  molecule. 
Gelatin  has,  therefore,  long  been  known  to  be  an  "abnormal" 
or  incomplete  protein,  and  its  value  in  nutrition  has  been  the 
subject  of  many  investigations. 

Drum  (5)  and  Munk  (6)  confirmed  the  earlier  observations 
that  a  part  of  the  protein  could  be  substituted  by  gelatin,  but 
that  when  it  forms  the  sole  source  of  nitrogen  there  is  always  a 
deficit. 


60       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Kossel  discovered  the  chemical  nature  of  the  protein  molecule 
to  be  a  chain-like  structure  consisting  of  a  number  of  amino- 
acids  linked  together,  the  amino  group  of  one  being  united  to  the 
carboxyl  group  of  its  neighbor  in  the  chain  through  abstraction 
of  the  elements  of  water.  Digestion  consists  of  the  addition  of 
the  elements  of  water  and  the  dissolution  of  the  union.  The 
correctness  of  this  view  was  proven  by  Curtius  and  by  E.  Fischer, 
through  synthesis,  under  the  guidance  of  KossePs  theory  (7). 

65.  Principal  Objectives  in  Researches  on  Protein  in  Nutri- 
tion.— Researches  in  the  field  of  protein  nutrition  during  the  last 
twenty-five  years  have  had  as  their  main  objectives  the  solu- 
tion of  the  following  problems:    1.  The  digestibility  of  the  pro- 
teins; 2.  the  number  and  nature  of  the  amino-acids  contained 
in  proteins  of  plant  and  animal  origin;  3.  the  amounts  of  each 
of  these  yielded  by  different  proteins ;  4.  the  extent  of  the  diges- 
tive decomposition  of  proteins  in  the  alimentary  tract;  5.  the 
ability  or  inability  of  the  tissues  to  synthesize  the  various  di- 
gestion products  of  proteins;  6.  the  immediate  disposition  of  the 
products  of  protein  digestion  after  absorption;  7.  the  chemical 
changes  which  take  place  during  the  catabolism  or  destruction 
of  the  amino-acids  in  the  body;  8.  the  capacity  of  the  body  to 
synthesize  protein  when  the  requisite  amino-acids  are  supplied 
in  the  food;  9.  the  determination  of  the  relative  efficiency  pos- 
sible in  the  transformation  for  purposes  of  growth  of  (a)  indi- 
vidual proteins  and  of  (b)  the  mixture  of  proteins  in  individual 
food-stuffs,  into  body  proteins;  10.  a  comparison  of  the  number 
and  kinds  of  amino-acids  required  in  the  process  of  repair  of 
tissue  waste,  an  essential  result  of  life  activities  with  those  re- 
quired in  the  formation  of  new  tissues  for  growth;  11.  the  physi- 
ological effects  of  nutrition  with  protein  intake  at  different  planes, 
or  the  discovery  of  the  amount  of  protein  from  stated  sources 
which  serves  to  maintain  the  body  in  optimal  nutritive  condition. 

It  is  not  within  the  scope  of  this  book  to  discuss  all  phases  of 
this  subject.  An  arbitrary  selection  of  topics  will  be  made,  and 
only  the  last  four  problems  will  be  considered.  This  is  desirable 
because  the  literature  relating  to  research  along  these  lines  is 
especially  in  need  of  being  summarized  and  interpreted. 

66.  Body   Can  Build  Proteins   from   Simple   Products  of 
Digestion. — The  problem  concerning  the  ability  of  the  tissues 
to  take  a  mixture  of  amino-acids  and  combine  them  into  pro- 
teins for  incorporation  into  living  protoplasm,  has  been  studied 
most  adequately  by  Abderhalden  (8) .    In  one  of  his  most  sue- 


NUTRITIVE  VALUE  OF  THE  PROTEINS  61 

cessful  experiments  a  dog  was  fed  during  100  days  upon  meat 
which  had  been  digested  to  the  amino-acid  stage  (erepton)  by 
the  successive  action  of  pepsin,  trypsin  and  erepsin,  the  protein- 
digesting  enzymes  of  the  stomach,  pancreas  and  intestine,  re- 
spectively. The  digested  meat  was  supplemented  with  non- 
nitrogenous  nutrients.  The  animal  remained  in  good  health  and 
gained  9.35  kg.  in  weight.  It  was  demonstrated  by  such  experi- 
ments that  protein  synthesis  is  possible  when  the  diet  furnishes 
all  the  essential  amino-acids  which  serve  as  structural  units  in 
the  formation  of  tissue  proteins. 

67.  Gelatin  Is  of  Value  When  Supplemented  with  Certain 
Ammo-Acids. — Kaufmann  (9)  conducted  the  first  experiment  of 
a  type  which  has  been  greatly  extended  by  others.  He  fed  dogs 
on  diets  in  which  gelatin  was  supplemented  with  tyrosin,  cys- 
tin  and  tryptophan  to  the  extent  of  4.2  and  1  per  cent  respec- 
tively of  the  total  nitrogen  of  the  diet,  the  remainder  being  sup- 
plied by  gelatin.  It  was  found  possible  with  this  mixture  to  re- 
place fully  the  protein  lost  through  metabolism.  These  results 
he  confirmed  by  experiments  on  himself.  In  1905,  when  his  in- 
vestigations were  made,  no  one  suspected  the  necessity  of  in- 
cluding in  the  diet  the  three  unidentified  dietary  factors  fat- 
soluble  A,  water-soluble  B  and  water-soluble  C,  which  are  con- 
cerned with  the  prevention  of  the  development  of  a  type  of 
ophthalmia,  polyneuritis  and  scurvy,  respectively.  His  experi- 
ments were  apparently  so  short  that  these  omissions  in  the  diet 
did  not  seriously  interfere  with  the  outcome  of  the  study. 

Abderhalden  (8)  sought  to  remove  certain  amino-acids  from 
completely  digested  proteins.  By  means  of  feeding  experiments 
with  the  protein  digestion  mixtures  rendered  incomplete,  in  that 
one  or  more  of  the  complexes  contained  in  tissue  proteins  were 
lacking,  he  sought  to  determine  which,  if  any,  of  the  digestion 
products  are  indispensable  in  the  diet.  The  object  was  to  de- 
termine whether,  in  certain  cases,  it  is  possible  for  the  body  to 
convert  one  amino-acid  into  another,  that  is,  to  synthesize  a 
missing  essential  complex.  He  was  able  to  remove  practically 
all  of  both  tyrosin  and  tryptophan  from  his  digestion  mixtures. 
The  former  of  these  is  a  cyclic  compound  and  the  latter  a  still 
more  complex  substance  containing  two  types  of  cyclic  struc- 
tures in  its  molecule.  Abderhalden  demonstrated  that  these  two 
amino-acids  must  be  furnished  in  the  diet  if  satisfactory  nutri- 
tion is  to  be  attained. 

Henrique  and  Hansen  (10)  published  similar  studies  which 


62       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

led  them  to  believe  that  the  three  diamino-acids,  arginin,  his- 
tidin  and  lysin,  are  not  necessary  in  the  nutrition  of  the  rat. 
Their  experiment  consisted  in  keeping  a  record  of  the  nitrogen 
intake  and  output  of  a  rat  during  a  period  of  23  days  while  the 
animal  was  restricted  to  a  diet  containing  only  digested  protein 
from  which  these  three  digestion  products  had  been  removed. 
It  is  very  difficult  to  avoid  loss  of  a  part  of  the  nitrogen  of  the 
urine  in  experiments  with  such  a  small  animal,  and  it  seems 
probable  that  their  work  was  not  free  from  error,  since  their 
results  are  at  variance  with  those  of  other  investigators.  They 
may  possibly  have  failed  to  remove  completely  from  their  pro- 
tein the  amino-acids  in  question. 

68.  The  Experiments  of  Willcock  and  Hopkins.— Willcock 
and  Hopkins  (11)  made  a  study  of  the  incomplete  protein,  zein, 
the  principal  protein  of  maize,  which  was  comparable  with  Kauf- 
mann's  studies  with  gelatin.     Zein  is  entirely  lacking  in  both 
lysin  and  tryptophan.    These  authors  fed  to  young  mice  diets 
of  purified  food  substances,  in  which  zein  was  the  sole  source  of 
protein  (amino-acids),  and  observed  that  the  animals  died  in 
less  than  14  days  in  a  state  of  torpor.    When  tryptophan  was 
added  to  the  food  they  lived  about  twice  as  long  and  remained 
lively  until  shortly  before  death.    The  addition  of  tyrosin  did 
not  improve  the  diet. 

Willcock  and  Hopkins  suggested  that  tryptophan  may  serve 
a  two-fold  function.  It  is  an  essential  structural  unit  of  the 
protein  molecules  of  which  the  tissues  are  formed,  and  is  per- 
haps a  precursor  of  a  substance  which  certain  tissues  elaborate. 
This,  they  suggested,  is  in  the  nature  of  a  hormone  or  regulator 
of  metabolism,  without  which  death  would  supervene  sooner 
than  through  specific  starvation  for  protein  alone. 

69.  Final  Proof  of  Protein   Synthesis. — Folin  and   Denis 
(12),  Van  Slyke  and  Meyer  (13),  and  Davis  and  Whipple  (14) 
have  shown  beyond  a  doubt  that  protein  is  readily  synthesized 
from  amino-acids,  for  in  the  intestine,  the  protein  is  digested  to 
the  amino-acid  stage,  and  the  identity  of  the  food  proteins  is 
lost.    In  the  process  of  growth,  in  the  regeneration  of  liver  tissue 
destroyed  as  the  result  of  chloroform  narcosis,  or  in  the  replace- 
ment of  the  complexes  in  the  tissues  lost  through  the  disintegra- 
tion of  certain  structures  in  normal  metabolism  of  protoplasm 
the  amino-acids  derived  from  food  protein  are  used  for  the  con- 
struction of  new  proteins  of  structures  different  from  those  of 
the  food. 

Mitchell  (15)  conducted  experiments  with  mice  fed  a  diet  mod- 


NUTRITIVE  VALUE  OF  THE  PROTEINS  63 

elled  after  one  which  was  extensively  employed  by  Osborne  and 
Mendel,  and  which  will  be  discussed  later.  In  this  diet  he  re- 
placed the  protein  by  a  definite  mixture  of  amino-acids.  The 
diet  contained  a  product  known  as  "protein-free  milk,"  which 
furnished  approximately  half  a  maintenance  ration  of  protein, 
but  this  fact  was  not  known  at  the  time.  The  efforts  to  keep  mice 
alive  on  this  diet  containing  from  eight  to  fifteen  amino.-acids 
were  unsuccessful.  This  was  in  part  due  to  the  failure  of  the 
animals  to  eat  a  sufficient  amount  of  the  food  to  meet  their 
energy  requirements.  It  was  found  necessary  to  feed  the  mice 
on  alternate  days  on  the  portion  of  the  food  mixture  minus  the 
amino-acids,  to  induce  them  to  take  a  greater  amount  of  food. 
He  found  the  omission  of  tryptophan  of  greater  significance 
than  that  of  other  amino-acids. 

70.  Does  Growth  Necessitate  Ammo-Acids  in  the  Diet  Not 
Essential  for  Maintenance?— Geiling   (16)    digested  casein  of 
milk  to  the  amino-acid  stage  and  then  precipitated  the  arginin, 
histidin  and  lysin  with  phosphotungstic  acid  as  Henrique  and 
Hansen  (10)  had  done,  and  conducted  experiments  in  feeding 
the  portion  of  the  protein  without  these  diamino-acids.     Mice 
were  used  as  experimental  animals.     His  diets  also  contained 
"protein-free  milk,"  which,  as  will  be  shown  later,  contained 
protein  nitrogen  (amino-acids)  sufficient  to  vitiate  in  great  meas- 
ure the  results  of  his  experiments.    Geiling  interpreted  his  find- 
ings as  indicating  that  arginin  and  histidin  are  interconvertible 
in  the  body.    He  also  concluded  that  lysin  is  not  necessary  for 
maintenance  without  growth.     These   observations  were  con- 
firmatory of  studies  made  by  Ackroyd  and  Hopkins  (17)  and  by 
Osborne  and  Mendel  (18). 

71.  The  Transmutability  of  Certain  Amino- Acids  into  Each 
Other. — Ackroyd  and  Hopkins  (17)  had  carried  out  feeding  ex- 
periments with  mice  fed  the  essential  non-nitrogenous  nutrients 
supplemented   with    simple   mixtures   of   purified    amino-acids. 
Their  conclusion  was  that  if  arginin  is  present  in  the  diet  his- 
tidin may  be  omitted,  and  vice  versa.    A  similar  relationship 
they  found  between  tyrosin  and  phenylalanin,  the  structural 
formulas  of  which  are  closely  similar.    This  was  the  first  instance 
where  it  was  believed  that  it  had  been  demonstrated  that  one 
amino-acid  may  be  converted  into  another. 

72.  Endogenous    and    Exogenous    Metabolism. — In    1905 
Folin  (19)  published  three  remarkable  papers  in  which  he  made 
it  clear  that  the  process  of  the  destruction  of  the  greater  part 
of  the  protein  which  is  digested  and  absorbed  daily,  and  of  its 


64       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

conversion  into  the  waste  products  which  constitute  the  normal 
components  of  the  urine,  differs  markedly  from  that  type  which 
is  involved  in  the  normal  functioning  of  the  tissues  of  the  living 
body.  The  end-product  of  the  first  type  is  principally  urea, 
while  creatinin  and  uric  acid  are  prominent  components  of  the 
latter.  When  a  diet  free  from  protein  or  other  nitrogenous 
compounds  is  taken  in  amount  sufficient  to  cover  the  energy  re- 
quirements of  the  body,  the  urine  will,  after  a  few  days,  con- 
tain about  60  per  cent  of  its  total  nitrogen  in  the  form  of  urea, 
18  per  cent  as  creatinin,  7.0  per  cent  as  ammonia,  and  3.4  per 
cent  as  uric  acid.  The  remainder,  which  will  amount  to  about 
12-14  per  cent  of  the  total,  is  in  forms  which  are  in  great  meas- 
ure uncharacterized,  and  which  cannot  as  yet  be  estimated  indi- 
vidually. A  urine  having  this  composition  represents  what  Folin 
termed  endogenous  metabolism,  to  distinguish  it  from  exogenous 
metabolism,  which  is  concerned  with  the  destruction  of  food 
protein  that  has  never  become  a  part  of  the  living  protoplasm 
of  the  body.  The  magnitude  of  the  endogenous  process  is  sur- 
prisingly constant,  whereas  that  of  the  latter  is  very  variable, 
and  is  determined  by  the  consumption  of  protein.  On  ordinary 
planes  of  nutrition,  exogenous  metabolism  or  destruction  of  food 
is  superimposed  upon  the  endogenous  or  tissue  waste  type  and 
the  composition  of  the  urine  gives  a  composite  picture  of  the  two. 

73.  An  Attempt  to  Differentiate  Between  Nutritional  Re- 
quirements for  "Repair"  Versus  Growth.— McCollum  (20)  at- 
tempted to  utilize  Folin's  discovery  as  a  means  of  studying  the 
problem  whether  an  amino-acid  supply  which  is  inadequate  for 
the  support  of  growth,  would  be  satisfactory  for  maintenance. 
A  farm  pig  was  given  a  nitrogen  free  diet  of  starch,  salts  and 
water  until  the  exogenous  metabolism  disappeared,  as  shown  by 
the  composition  of  the  urine.  In  a  subsequent  period  a  definite 
amount  of  an  incomplete  protein  such  as  gelatin  or  zein  was  to 
be  added  to  the  experimental  diet  of  carbohydrate,  salts  and 
water.  From  the  increase  in  the  nitrogen  output  in  the  urine 
and  from  the  change  in  the  forms  in  which  it  appeared,  it  was 
believed  to  be  possible  to  decide  to  what  extent,  if  at  all,  the 
amino-acids  of  the  incomplete  protein  were  utilized. 

It  was  found  that  young  swine,  which  were  used  as  experi- 
mental animals,  readily  ate  a  sufficient  amount  of  the  nitrogen 
free  diet  to  cover  their  energy  requirements,  and  could  easily  be 
brought  into  the  condition,  in  which  they  exhibited  only  the 
endogenous  type  of  metabolism.  When  to  pigs  in  this  condi- 


NUTRITIVE  VALUE  OF  THE  PROTEINS  65 

tion,  a  known  amount  of  nitrogen  in  the  form  of  urea,  an  end 
product  of  metabolism,  was  added  to  the  diet  it  was  all  recov- 
ered in  the  urine  in  addition  to  the  amount  derived  from  endoge- 
nous sources.  The  percentage  composition  of  the  urine  with 
respect  to  creatinin  and  urea  showed  the  expected  alterations 
the  former  representing  less  and  the  latter  more  of  the  total 
nitrogen  of  the  urine. 

When,  instead  of  urea,  gelatin  or  zein  was  administered  in 
quantities  sufficient  to  supply  exactly  the  amount  of  nitrogen 
derived  from  endogenous  metabolism,  the  nitrogen  from  these 
"incomplete"  proteins  was  only  in  part  excreted  in  the  urine  in 
addition  to  the  amount  derived  from  endogenous  sources.  The 
results  showed  that  60  per  cent  of  the  nitrogen  of  gelatin  was 
excreted  and  40  per  cent  retained  for  some  purpose  in  the  tissues, 
presumably  for  the  partial  repair  of  tissue  waste.  Under  the 
same  experimental  conditions  73  per  cent  of  the  nitrogen  of  zein 
was  retained  and  27  per  cent  excreted  in  addition  to  the  amount 
expected  from  endogenous  sources. 

74.  Experiments  on  the  Synthesis  of  Ammo-Acids  from 
Ammonia. — Almost  simultaneously  Grafe  (21)  announced  that 
nitrogen  equilibrium  could  be  attained  on  a  diet  of  carbohydrate 
and  ammonium  acetate.  Abderhalden  (22)  repeated  this  work 
and  found  a  partial  utilization  of  ammonium  salts  for  replacing 
the  nitrogen  lost  through  tissue  waste,  but  denied  the  possibility 
of  attaining  nitrogen  equilibrium.  Underbill  and  Goldschmidt 
(23)  confirmed  the  view  that  there  is  under  these  conditions  a 
sparing  action  of  body  protein  by  ammonium  citrate,  but  all  the 
tissue  loss  could  not  be  replaced  from  nitrogen  in  the  form  of  am- 
monium salts.  In  all  these  studies  we  now  know  that  the  diets 
employed  were  deficient  in  the  three  vitamins,  fat-soluble  A, 
water-soluble  B,  and  water-soluble  C,  so  the  interpretation  of 
the  results  are  not  now  as  satisfactory  as  they  once  appeared 
to  be. 

It  has  been  abundantly  demonstrated  by  several  workers,  that 
the  simplest  of  the  amino-acids,  glycocoll,  is  readily  synthesized 
by  the  body  tissues  (24).  Casein  contains  no  glycocoll,  yet  it 
is  a  complete  protein,  and  can  meet  all  the  requirements  of  an 
animal  for  nitrogen  in  the  form  of  amino-acids.  From  these  re- 
sults it  is  safe  to  conclude  that  the  tissues  of  the  higher  animals 
are  capable  of  synthesizing  certain  amino-acids,  and  that  these 
are  made  use  of  in  some  way  to  conserve  the  body  proteins,  even 
though  the  list  which  can  be  so  synthesized  is  incomplete.  It 


66       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

appears  certain  that  tyrosin,  tryptophan,  and  probably  all  the 
other  cyclic  amino-acids  and  cystin  cannot  be  synthesized  by 
the  mammal  (25).  Abderhalden  suggested  that  the  sparing  ac- 
tion of  ammonium  salts  is  due  to  prevention  of  destruction  of 
some  of  the  amino-acids  derived  from  the  tissues,  and  that  these 
may  be  used  over  again. 

75.  Attempts  to  Prove  the  Superiority  of  Proteins  of  One's 
Own  Species  over  Foreign  Proteins  in  Nutrition. — Michaud 
(26)  sought  to  verify  with  experiments  on  dogs,  the  theory  that 
the  more  similar  the  food  proteins  to  those  of  the  tissues  which 
they  are  destined  to  form  in  the  body,  the  higher  would  be  their 
biological  value  as  nutrients.     He  allowed  dogs  to  fast  for  a 
time  to  reduce  their  nitrogen  output  to  the  minimum  of  tissue 
destruction.    He  then  fed  them  a  non-nitrogenous  diet  supple- 
mented with  various  amounts  of  protein  from  different  sources. 
His  findings  lead  us  to  the  belief  that  the  proteins  of  the  same 
species  of  animal  are  superior  in  dietary  value  to  proteins  ob- 
tained from  another  species  or  from  plants.    Dog  muscle  and  dog 
serum  proteins  were  of  higher  nutritive  worth  for  the  dog  than 
muscle  or  serum  proteins  from  the  horse.     A  mixture  of  dog 
tissues  (muscle,  blood  and  glandular  organs)  was  also  superior 
to  any  of  the  other  proteins  studied.    Gliadin  and  edestin,  pro- 
teins from  the  wheat  kernel  and  hempseed  respectively,  were  of 
the  lowest  value.     We  now  know  that  his  diets  were  by  no 
means  comparable  in  their  quality  with  respect  to  factors  other 
than  protein.    All  except  those  in  which  the  glandular  organs 
were  included  were  very  deficient  in  the  anti-neuritic,   anti- 
ophthalmic  and  anti-scorbutic  substances,  as  well  as  very  poor 
in  their  mineral  content.    It  is  not  possible,  therefore,  to  accept 
without  doubt  his  interpretation  of  his  results. 

76.  Comparative  Nutritive  Values  of  Individual  Proteins. 
— During  the  past  decade  numerous  experiments  have  been  con- 
ducted with  a  view  to  determining  the  relative  nutritive  values 
of  a  large  number  of  individual  proteins.    The  proteins  studied 
were  in  the  greater  number  of  instances  those  which  are  the 
easiest  to  prepare  in  quantity  in  a  state  of  purity  from  substances 
of  animal  or  vegetable  origin.    The  most  prominent  investigators 
who  have  pursued  this   line   of   inquiry    are   Osborne   of  the 
Connecticut  Agricultural    Station   and   Mendel   of   Yale   Uni- 
versity. 

It  has  been  pointed  out  in  Chapter  II  that  these  investigators 
first  sought  to  make  comparative  studies  of  isolated  proteins  by 
adding  them  to  a  mixture  of  purified  carbohydrates,  fats,  mineral 


NUTRITIVE  VALUE  OF  THE  PROTEINS  67 

salts  and  water,  and  invariably  met  with  failure,  for  in  every  in- 
stance the  animals  suffered  steady  decline.  After  their  failure 
with  the  diet  composed  entirely  of  purified  food  substances,  every 
component  of  which  was  known,  they  began  a  series -of  studies 
with  what  they  believed  to  be  essentially  the  equivalent  of  a 
purified  food  mixture.  This  involved  the  inclusion  in  the  diet  of 
about  28  per  cent  of  a  product  which  they  called  "protein-free 
milk."  On  several  occasions  it  was  pointed  out  by  McCollum 
that  the  properties  of  this  product  were  such  as  to  seriously 
impair  their  results  (27).  Osborne  and  Mendel  apparently 
thought  that  this  criticism  was  not  well  founded,  for  they  con- 
tinued to  employ  "protein-free  milk"  in  almost  all  of  their  work 
during  a  period  of  seven  years,  and  without  successfully  justi- 
fying its  use.  They  finally  abandoned  the  use  of  the  product  in 
1917,  at  which  time  they  adopted  essentially  the  method  of 
study  which  had  been  described  by  McCollum  and  Davis  in 
1915  (28). 

77.  Osborne  and  Mendel's  Studies  on  Protein  Metabolism. 
— There  were  three  principal  phases  of  protein  nutrition  which 
Osborne  and  Mendel  discussed  in  the  light  of  their  data.    The 
importance  of  their  deductions  is  so  great  and  the  defects  in  their 
method  so  difficult  for  the  inexperienced  to  appreciate,  that  a 
somewhat  full  discussion  is  warranted  of  the  manner  in  which 
"protein-free  milk"  vitiated  a  considerable  part  of  a  research  of 
a  most  comprehensive  type.     Three  phases  of  protein  metabo- 
lism will  be  discussed  here:    The  comparative  values  of  the  in- 
dividual proteins  in  growth;  the  protein  requirements  of  the 
animal  body  in  maintenance  as  contrasted  with  growth;   the 
possibility  of  the  existence  for  the  maintenance  of  the  species  of 
a  synthetic  capacity  in  the  maternal  organism,  through  the  me- 
dium of  the  placenta  and  of  the  mammary  gland,  which  cannot 
be  affected  by  other  body  tissues  for  the  maintenance  of  the 
life  of  the  individual.     These  will  be  considered  in  the  order 
enumerated. 

78.  Methods  of  Comparing  the  Biological  Values  of  Indi- 
vidual Proteins. — One  method  which  they  employed  to  illustrate 
the  striking  differences  in  the  values  of  the  proteins  from  different 
sources  for  the  support  of  growth,  was  that  of  feeding  a  series 
of  groups  of  animals  on  a  diet  of  constant  composition,  but  with 
a  different  protein,  carefully  isolated  and  purified,  as  a  compo- 
nent in  the  diet  of  each  experimental  group.     The  amount  of 
growth  or  of  loss  in  body  weight  of  the  animals  during  the  first 
thirty  days  on  the  experimental  diets  was  recorded  and  made 


68       THE  NEWER  KNOWLEDGE  OF  NUTRITION 


Grams 


I        8 

c 

£ 
Phase 

Zein, 
Gelati 
Congl 
->>Rye, 
^}Hor 
±jLe 

=4" 

=^}v 

» 

i           £ 
lin,  be 
naize 

ten,  lu 
gliadin 
iein,  ba 
"umin, 

adin,  v 

gnin,  F 
-*}Leg 

j> 

| 

n 

ine 

ley 
ea 

heat 

iimelin. 
jrlutelin 

>Edes 

i 

pea 
hemp 

in,  hen 

nin.  be 
utenin, 
obulin, 
actalbu 

Gluten 
}  Excel 

\  Qlobu 

t       i 

eed 
pseed 

in 

wheat 

:ottons< 
nin,  mi 

>,  maiz 
!in,  Bra 

lin,  squ 
,  egg 

isein,  m 
}0vovi 

i 

ed 

k 

:il  nut 
ish  seed 

ilk 

«llin,  egg  yolk 

1 

-^}  Glyc 

i 

*  rG 

\  f> 

>/  G 

--»  1 

'  k 

*  »j 

ilbumir 

J- 

„ 

r~* 

The  above  table  is  slightly  modified  from  a  publication  by 
Osborne  and  Mendel,  Zeit,  if.  physiol.  Chem.;  1912,  Ixxx,  307, 


NUTRITIVE  TALUE  OF  THE  PROTEINS  69 

the  basis  of  comparison.     The  diet  consisted  of  the  following 
substances: 

Purified  protein    18.0  per  cent 

"Protein-free    milk"    28.2  "       " 

Starch    20.8  "       " 

Agar-agar    5.0  "       " 

Fat    .                                                                     ...  28.0  "       " 


The  results  obtained  with  a  series  of  proteins  are  shown  in 
graphic  form  in  the  diagram  on  page  68. 

An  inspection  of  this  table  shows  that  animals  restricted  to 
bean  protein  lost  weight  rapidly.  Those  fed  zein,  the  principal 
protein  of  the  maize  .kernel,  and  also  those  fed  gelatin  lost  weight, 
but  not  so  rapidly.  Conglutin,  a  protein  from  the  lupine,  and 
gliadin  of  rye,  served  to  maintain  weight  without  growth,  and 
little  growth  was  secured  with  hordein  of  barley  or  legumin  of 
pea.  All  the  other  proteins  listed  were  capable  of  promoting 
growth  when  fed  with  the  other  substances  in  the  diet. 

A  second  method  which  Osborne  and  Mendel  employed  for  the 
comparison  of  the  biological  values  of  different  proteins  for 
growth  in  the  rat,  was  to  observe  the  rapidity  of  growth  of  the 
animals  when  fed  diets  of  the  type  described  above,  in  which  but 
a  single  protein  was  added,  the  character  of  the  protein  varying 
in  different  experiments  (30).  A  third  method  was  to  carefully 
establish  the  amount  of  increase  in  body  weight  which  was  pos- 
sible as  the  result  of  the  consumption  of  a  definite  amount  of 
protein,  the  nature  of  the  remainder  of  the  food  mixture  remain- 
ing essentially  constant  throughout  the  series  of  experiments  (31). 
As  an  illustration  of  the  results  secured  by  the  latter  method  the 
following  table  is  representative: 


Rat                    Diet 

Initial 
body 
weight 

Gain 

Intake  of 

Total 
food 

Protein 

2115    9%   lactalbumin 

grams 
65 
43 
59 
60 
42 
52 
42 
41 
59 
83 
65 

grams 
99 
89 
91 
93 
59 
60 
44 
54 
-3 
14 
29 

days 
80 
80 
80 
80 
80 
80 
80 
80 
80 
80 
80 

grams 
589 
395 
575 
560 
435 
465 
371 
454 
366 
459 
464 

grams 
43.7 
29.3 
42.6 
41.5 
35.2 
38.9 
13.8 
16.8 
14.8 
19.2 
19.4 

2123      "             "           

2207      "             "           

2210      "             "           

2051    9%  casein  (cow's  milk). 
2110    9%  edestin  (hemp  seed) 
2044    4y2%   lactalbumin  (milk) 
2049    4%%    lactalbumin  

2118    4M$%    casein     

2113    4%%    edestin  

2114    4%%    casein  

70       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

It  will  be  observed  that  rats  which  ate  similar  amounts  of  food 
grew  much  faster  on  9  per  cent  of  lactalbumin  than  on  casein  or 
edestin.  Similar  differences  were  observed  when  the  lower  pro- 
tein intake  was  fed.  At  the  time  these  experiments  were  carried 
out  it  was  believed  by  Osborne  and  Mendel  that  they  actually 
represented  quantitative  comparisons  of  the  values  of  these  pro- 
teins for  growth.  It  will  be  apparent  from  data  discussed  later 
in  this  chapter  in  connection  with  the  nutritive  value  of  gliadin, 
that  lactalbumin  as  the  sole  source  of  protein  cannot  support 
any  growth  whatever.  Its  excellent  showing  in  the  above  experi- 
ments was  due  to  the  supplementary  action  of  the  amino-acids 
contained  in  the  "protein-free  milk"  which  was  fed  with  it. 

79.  "Protein-Free  Milk"  a  Disturbing  Factor  in  These  Ex- 
periments.— Since  the  nitrogen  contained  in  "protein-free  milk" 
can  act  as  a  source  of  certain  amino-acids,  it  is  obvious  that  the 
true  dietary  value  of  any  series  of  proteins  which  it  is  desired 
to  compare  cannot  be  secured,  when  they  are  studied  by  the 
method  involving  the  concomitant  feeding  of  this  material.    The 
scope  of  the  studies  of  Osborne  and  Mendel,  and  the  importance 
of  the  deductions  which  have  been  drawn  from  them  are  so 
great  that  a  detailed  exposition  of  the  action  of  the  nitrogenous 
constituents  of  "protein-free  milk"  in  vitiating  their  results  will 
be  presented.    This  is  best  brought  out  by  their  studies  of  the 
nutritive  value  of  gliadin,  one  of  the  principal  proteins  of  the 
wheat  kernel.     These  are  of  fundamental  importance  because 
their  interpretation  involves  the  question,  not  only  of  the  biologi- 
cal value  of  "protein-free  milk"  as  a  source  of  amino-acids,  and 
its  bearing  on  the  recorded  nutritive  significance  of  numerous 
proteins,  but  likewise  on  the  problem  whether  the  processes  of 
maintenance  without  growth,  or  the  repair  of  tissue  waste,  is  of 
a  lower  order  than  those  of  growth  requiring  fewer  amino-acids 
than  the  latter. 

80.  Properties  of  Protein-Free  Milk.— "Protein-free  milk" 
was  prepared  by  acidifying  with  acetic  acid,  milk  which  had 
been  freed  from  fat  by  centrifuging.    The  resulting  whey,  after 
the  removal  of  the  casein  which  flocks  out  on  the  addition  of 
acid,  was  next  heated  to  boiling  to  coagulate  the  lactalbumin. 
These  are  the  principal  proteins  of  milk,  and  with  their  removal 
about  93  per  cent  of  the  total  nitrogen  contained  in  the  milk  is 
abstracted.     The  solution  which  was  filtered  free  from  lactal- 
bumin was  evaporated  to  dryness,  leaving  a  yellowish  residue 
consisting  of  milk  sugar,  most  of  the  salts  of  the  milk,  and  a 


NUTRITIVE  VALUE  OF  THE  PROTEINS  71 

certain  amount  of  nitrogenous  compounds  for  the  separation  of 
which  no  method  is  known. 

Osborne  and  Mendel  held  the  view,  which  their  own  studies 
finally  showed  to  be  untenable  (32),  that  the  amount  of  protein 
or  its  equivalent,  resulting  from  the  digestion  of  milk  protein  or 
directly  secreted  by  the  mammary  gland,  which  was  contained  in 
their  "protein-free  milk"  was  too  small  to  be  a  factor  of  signifi- 
cance in  their  experiments.  The  final  product  they  included  in 
their  diets  contained  about  0.7  per  cent  of  nitrogen  (30),  which 
would  be  equivalent,  if  it  were  all  in  the  form  of  protein  or  of 
its  digestion  products,  to  4.37  per  cent  of  dry  matter.  It  is  well 
known  that  some  urea,  purins,  creatin,  and  other  simple  nitro- 
genous substances  which  circulate  in  the  blood  are  always  found 
in  milk.  It  is  certain,  however,  that  there  is  a  considerable 
amount  of  nitrogen  in  "protein-free  milk"  in  forms  yielding 
amino-acids  in  the  body.  Its  property  of  enhancing  certain  in- 
complete proteins  makes  this  view  imperative. 

From  what  has  been  said  in  Chapter  II  it  will  be  clear  that  a 
protein  which  is  of  low  biological  value  for  growth  because  of  the 
fact  that  one  or  more  of  the  digestion  products  which  it  contains 
is  present  in  too  small  an  amount  to  make  possible  its  efficient 
transformation  into  body  proteins,  may  be  greatly  enhanced  in 
growth  promoting  value  by  the  addition  of  the  missing  amino- 
acid  or  acids.  This  has  been  illustrated  in  the  case  of  gelatin 
and  for  the  meat  digests  prepared  by  Abderhalden  (p.  61).  It 
will  be  readily  understood,  therefore,  that  when  a  series  of  puri- 
fied proteins  was  fed  to  young  animals,  the  remainder  of  the  diet 
consisting  of  28  per  cent  of  "protein-free  milk,"  together  with 
non-nitrogenous  nutrients  similar  to  the  following: 

Protein    18.0  per  cent. 

"Protein-free   milk"    282  «       « 

Starch    20.8  "       " 

Agar-agar 5.0  "       " 

Fat    28.0  "       " 

the  amino-acids  furnished  by  the  "protein-free  milk"  may  im- 
prove the  quality  of  some  or  all  of  the  pure  proteins,  and  so 
change  the  experimental  results  as  to  make  it  unwarrantable  to 
draw  any  conclusions  concerning  their  relative  nutritive  values 
when  fed  without  such  an  amino-acid  supplement. 

81.  Milk  Contains  Protein-Digesting  Enzymes. — Babcock 
and  Russell  (33)  and  Freudenreich  (34)  demonstrated  in  milk 


72       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

the  presence  of  protein  digesting  enzymes.  The  bacteria  found 
in  all  market  milks  are  in  many  instances  capable  of  digesting 
proteins.  There  is,  therefore,  abundant  opportunity  for  milk 
used  for  the  preparation  of  "protein-free  milk"  after  it  has  been 
kept  for  an  interval  of  24  hours  or  more  to  contain  partial  diges- 
tion products  of  protein  that  would  not  be  removable  by  acidify- 
ing or  by  coagulating.  All  such  compounds  would  remain  in 
the  final  product. 

Osborne  and  Mendel  felt  justified  by  the  work  of  Munk  (35) 
in  assuming  that  the  0.7  per  cent  of  nitrogen  in  "protein-free 
milk"  was  not  a  disturbing  factor  in  their  experimental  studies. 
Munk  had,  twenty  years  previously,  sought  by  coagulation  and 
by  precipitation  with  various  reagents,  to  determine  the  amount 
of  "non-protein"  nitrogen  in  milk  (36).  He  arrived  at  the  con- 
clusion that  one-fifteenth  of  the  total  nitrogen  in  milk  is  in 
forms  other  than  protein.  Osborne  and  Mendel  accepted  this 
figure  as  correct  and  reasoned  as  follows:  A  certain  amount  of 
milk  contains  a  known  amount  of  nitrogen,  a  part  of  which  is  in 
the  form  of  proteins  and  can  be  removed  by  the  methods  em- 
ployed. On  evaporating  the  resulting  whey  to  dryness  the  "pro- 
tein-free milk"  which  remains  contains  0.7  per  cent  of  nitrogen  in 
forms  not  known.  From  the  weight  of  "protein-free  milk"  ob- 
tained, the  total  nitrogen  it  contained  was  calculated.  From 
this  amount  they  subtracted  one-fifteenth  of  the  total  nitrogen 
contained  in  the  milk  with  which  they  started.  The  remainder 
was  assumed  to  represent  "protein,"  or  nitrogen  having  a  nutri- 
tive value.  There  is  no  evidence  in  Munk's  data,  or  in  any  fur- 
nished by  Osborne  and  Mendel  to  show  that  the  one-fifteenth  of 
the  total  nitrogen  of  milk,  which  remained  after  the  removal  of 
the  casein  and  lactalbumin,  and  which  was  disposed  of  by  mathe- 
matical treatment  of  their  analytical  data,  was  not  a  source  of 
amino-acids,  and  capable,  therefore,  of  enhancing  the  nutritive 
value  of  poor  proteins  making  them  appear  to  have  higher  bio- 
logical values  than  they  possessed. 

A  diet  such  as  was  used  in  their  studies,  and  which  contained 
18  per  cent  of  added  protein  in  purified  form,  together  with  28 
per  cent  of  "protein-free  milk,"  would  derive  93  per  cent  of  its 
total  nitrogen  from  the  former  and  7  per  cent  from  the  latter 
source.  The  biological  evidence  is  conclusive  that  this  7  per 
cent  of  the  nitrogen  of  their  diets  supplemented  certain  proteins 
with  which  it  was  fed,  in  a  very  effective  manner  and  led  to  en- 
tirely erroneous  conclusions.  This  is  well  illustrated  by  the  way 


NUTRITIVE  VALUE  OF  THE  PROTEINS  73 

in  which  it  supplements  gliadin,  one  of  the  principal  proteins  of 
wheat,  and  lactalbumin  of  milk. 

82.  Are  Fewer  Amino-Acids  Essential  for  Maintenance 
Than  Are  Required  for  Growth? — In  1912  Osborne  and  Mendel 
(37)  performed  an  experiment  which  they  interpreted  as  demon- 
strating the  processes  of  maintenance  as  being  of  a  lower  order 
than  those  of  growth,  and  that  repair  of  tissue  waste  can  be 
effected  without  the  amino-acid  lysin,  whereas  this  complex  is 
indispensable  for  growth.  There  were  two  confusing  factors  in 
this  experiment,  the  "protein-free  milk"  nitrogen,  and  the  erro- 
neous belief  that  gliadin  contained  but  very  little  lysin. 

Osborne  had  carefully  determined  the  amounts  of  lysin  in 
numerous  proteins  and  had  found  the  content  of  this  substance  in 
gliadin  to  be  0.15  per  cent.  This  amount  is  extremely  small  com- 
pared with  the  yields  obtainable  from  many  other  proteins,  not- 
ably those  of  animal  tissues.  This  is  illustrated  by  the  following 
table  (38): 

LYSIN  IN  PROTEINS 

Lactalbumin    8.10  per  cent.      Glutelin  (maize)   2.93  per  cent. 

Halibut  muscle    7.45  Glutenin   (wheat)....  1.92 

Ox  muscle  7.59  Edestin  (hemp  seed) .  1.65 

Casein  (cow's  milk)..  7.61  Amandin  (almond)...  0.72 

Vitellin  (egg  yolk)...  4.81  Gliadin  (wheat) 0.16 

Albumin  (hen's  egg).  3.76  Hordein  (barley)  0.00 

Legumin   (pea)    4.98  Zein  (maize)  0.00 

Phaseolin  (Kidney 
bean)    4.58 

In  the  experiment  just  referred  to  they  restricted  young  rats 
to  a  diet  consisting  of  gliadin  18.0,  "protein-free  milk"  28.2, 
starch  20.8,  agar-agar  5.0  and  lard  28.0  per  cent.  The  animals 
were  able  to  maintain  their  weight  during  periods  as  long  as  500 
days,  but  were  unable  to  grow  to  any  appreciable  extent.  When 
lysin,  one  of  the  eighteen  digestion  products  of  nearly  all  pro- 
teins, was  added  to  the  diet  to  the  extent  of  3  per  cent  of  the 
protein  content,  the  animals  were  capable  of  normal  develop- 
ment. 

At  the  time  these  experiments  were  conducted  with  gliadin  it 
was  assumed  that  this  protein  contained  but  0.16  per  cent  of 
lysin.  However,  Osborne,  Van  Slyke,  Leavenworth  and  Vino- 
grad  (39)  in  1915  made  new  analyses  of  gliadin  and  other  pro- 
teins, by  a  more  satisfactory  method  than  that  which  Osborne 
had  earlier  employed  (40).  They  found  that  gliadin  contains 


74       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

about  1.21  per  cent  of  lysin,  or  about  seven  times  what  it  was 
assumed  to  contain  at  the  time  when  the  conclusion  was  drawn 
from  feeding  experiments  with  this  protein,  that  lysin  is  not 
necessary  for  maintenance  without  growth.  With  this  knowl- 
edge available,  and  with  the  fact  made  evident  that  the  nitrogen 
of  "protein-free  milk"  in  the  quantities  used  in  their  experiments, 
amounts  to  about  half  the  maintenance  requirement  of  a  young 
animal,  there  is  no  longer  any  reason  to  regard  these  data  as 
having  any  bearing  on  the  problem  of  the  possible  dissimilarity 
in  the  amino-acid  requirements  for  the  processes  of  maintenance 
as  contrasted  with  those  of  growth. 

83.  Is  the  Mammary  Gland  Able  to  Synthesize  the  Amino 
Acid  Lysin? — The  observation  that  a  female  rat  which  had  been 
restricted  during   178   days  to   a   diet  containing   gliadin   and 
"protein-free  milk,"  was  able  to  become  pregnant  and  produce 
four  young  and  to  suckle  these  to  the  age  of  23  days,  was  also 
presented  as  evidence  that  maintenance  or  the  development  of 
young  in  the  uterus,  and  the  formation  of  milk  with  which  to 
nourish  the  young  following  their  birth,  are  possible  on  a  diet 
lacking  in  lysin  and  incapable  of  supporting  growth.    From  what 
has  been  said  previously  as  to  the  actual  content  of  lysin  in 
gliadin  and  the  nutritive  value  of  the  nitrogen  of  "protein-free 
milk"  it  will  be  appreciated  that  the  data  tend  rather  to  support 
the  view  that  no  differentiation  can  be  made  of  the  nutritive 
needs  of  an  animal  during  growth  as  contrasted  with  an  adult 
drawing  sustenance  for  the  performance  of  the  functions  of  re- 
production and  the  rearing  of  young.    This  mother  was  simply 
being  nourished  on  the  lowest  intake  of  lysin  possible  for  her 
requirements  under  the  experimental  conditions. 

84.  The  Ammo-Acid  Lysin  Is  the  Limiting  Factor  De- 
termining the  Value  of  Certain  Proteins. — There  is  no  room 
to  doubt  that  lysin  is  the  limiting  factor  in  this  diet,  but  gliadin 
furnished  decidedly  more  of  this  amino-acid  than  was  at  the 
time  supposed.     Some  indication  of  the  nutritive  value  of  the 
nitrogenous  compounds  of  "protein-free  milk"  is  afforded  by 
experiments  carried  out  by  McCollum  and  Davis  (27).    They 
showed  that  young  rats  slowly  lose  weight  when  confined  to  a 
diet  in  which  the  entire  protein  content  limited  to  1.5  per  cent 
of  the  food  mixture,  was  derived  entirely  from  skim  milk  powder. 
The  young  rats,  however,  maintain  weight  over  considerable  pe- 
riods when  the  amount  of  milk  proteins  is  increased  to  3  per  cent 
of  the  food  mixture.    On  the  other  hand,  1.5  per  cent  of  milk  pro- 


NUTRITIVE  VALUE  OF  THE  PROTEINS  75 

tein  supplemented  with  nitrogen  equivalent  to  1.5  per  cent  of 
protein  derived  from  "protein-free  milk"  served  to  maintain  the 
animals  approximately  as  well  as  did  3  per  cent  from  milk  pow- 
der. From  this  observation  they  drew  the  conclusion  that  the 
nitrogen  in  "protein-free  milk"  has  approximately  the  same  nu- 
tritive value  as  that  contained  in  milk  proteins.  This  would  not 
necessarily  be  true  when  it  serves  as  the  sole  source  of  nitrogen 
in  the  diet,  but  it  is  when  this  product  is  combined  with  the  pro- 
teins of  milk  in  equivalent  amount. 

85.  The  Residual  Nitrogen  of  Protein-Free  Milk  Can  Sup- 
plement Certain  Incomplete  Proteins. — The  most  striking  illus- 
tration of  the  value  of  the  nitrogen  of  "protein-free  milk"  as  a 
source  of  amino-acids  is  seen  in  its  supplementary  relation  to 
lactalbumin.     The  comparative  values  of  casein,  edestin  and 
lactalbumin  when  fed  supplemented  with  this  product  are  shown 
on  page  69.     These  indicated  that  lactalbumin  was  far  supe- 
rior to  either  of  the  other  proteins  for  growth.    A  similar  result 
was  observed  in  experiments  designed  to  show  the  smallest  intake 
of  each  of  these  proteins  which  would  just  serve  to  maintain 
young  rats  in  weight  equilibrium   (41).     In  these  experiments 
diets  were  employed,  having  a  composition  similar  to  that  de- 
scribed in  connection  with  the  gliadin  studies  and  containing  28 
per  cent  of  "protein-free  milk."    In  some  instances,  however,  but 
2  per  cent  of  purified  protein  were  added  to  the  food  mixture. 
In  such  cases  the  nitrogen  of  the  purified  protein  amounted  to 
only  37  per  cent  of  the  total,  the  remaining  63  per  cent  being 
derived  from  the  "protein-free  milk."     In  the  interpretation  of 
the  results  no  account  was  taken  of  this  latter  increment.    Under 
these  experimental   conditions   lactalbumin   appeared  to   be   a 
protein  of  extraordinary  value. 

86.  Lactalbumin  an  Incomplete  Protein. — McCollum,  Sim- 
monds  and  Parsons  (42)  restricted  young  rats  to  a  diet  which 
contained  lactalbumin  as  the  sole  source  of  nitrogen  and  could 
not  secure  any  growth,  even  with  18  per  cent  of  protein  in  the 
diet.    They  drew  the  obvious  conclusion  that  since  the  same 
diet  was  complete  when  casein  replaced  the  lactalbumin,  the 
latter  must  be  a  poorly  constituted  protein.    This  has  been  con- 
firmed by  Emmett  and  Luros  (43).    A  later  experience  of  Os- 
borne  and  Mendel  (32)  convinced  them  also  that  lactalbumin 
was  lacking  in  some  constituent  which  is  essential  in  proteins 
of  the  "complete"  type.    They  found  a  diet  consisting  of  purified 
food  substances,  including  18  per  cent  of  lactalbumin,  inadequate 


76       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

for  the  support  of  growth  even  when  small  additions  of  yeast 
proteins  were  present  in  the  diet.  Yeast  proteins  do  not  appear 
to  supplement  lactalbumin,  whereas  the  small  amount  of  nitrog- 
enous substances  in  "protein-free  milk"  are  very  effective  for 
this  purpose.  In  this  connection  Osborne  and  Mendel  state 
"For  some  as  yet  unknown  reason  the  majority  of  the  rats  grew 
normally  (on  the  diets  containing  "artificial  protein-free  milk," 
butter  fat,  starch,  lard  and  yeast)*  when  the  protein  used  was 
casein,  whereas  they  have  usually  failed  when  it  was  edestin, 
and  almost  invariably  when  lactalbumin,  cottonseed  globulin, 
cottonseed  proteins,  or  squash  seed  globulin  was  fed.  This  result 
surprised  us  because  all  of  these  proteins  had  earlier  led  to  nor- 
mal growth  when  used  in  rations  containing  natural  "protein- 
free  milk."  The  failure  to  grow  on  the  "artificial  protein-free 
milk"-yeast  was  especially  unexpected  in  the  case  of  lactal- 
bumin for  our  former  experience  had  demonstrated  that  even 
exceptionally  small  amounts  of  this  protein  promoted  normal 
growth."  It  is  certain  that  any  experiments  directed  toward 
making  a  quantitative  comparison  of  the  nutritive  values  of 
isolated  proteins,  have  in  them  a  disturbing  factor  wherever 
"protein-free  milk"  was  employed. 

87.  The  Nitrogen  of  Protein-Free  Milk  Is  in  Part  in  the 
Form  of  Amino-Acids. — Chemical  studies  which  contribute  to 
our  knowledge  of  the  nature  of  the  nitrogenous  constituents  of 
"protein-free  milk"  have  been  made  by  Osborne  and  Wakeman 
(44),  Denis  and  Minot  (45)  and  Kennedy  (46). 

It  should  not  be  inferred  from  the  above  critical  review  of  the 
role  played  by  "protein-free  milk"  in  their  experiments,  that  the 
numerous  studies  conducted  by  Osborne  and  Mendel,  in  which 
this  product  was  used,  are  without  significance.  Quite  the  reverse 
is  true.  They  serve  admirably  to  emphasize  the  variations  which 
exist  in  the  nutritive  values  of  proteins  from  different  sources. 
They  leave  no  room  for  doubt  that  in  a  number  of  proteins  from 
vegetable  sources  lysin  is  the  limiting  factor  which  determines 
their  value  for  growth.  They  demonstrate  that  the  sulphur-con- 
taining amino-acid,  cystin,  is  the  limiting  factor  in  casein,  and 
that  the  supplements  which  are  essential  in  order  to  render  zein 
nutritively  complete  are  lysin  and  tryptophane.  Even  when 
these  are  added,  however,  and  the  protein  is  made  adequate  for 
growth,  it  is  still  further  improved  by  the  addition  of  the  diamino- 
acid,  arginin.  They  established  the  principle  that  the  nutritive 

*  Parenthetical  expression  the  author's. 


NUTRITIVE  VALUE  OF  THE  PROTEINS  77 

value  of  a  protein  depends  upon  the  quality  and  quantity  of  the 
amino-acids  which  it  yields.  Their  studies  failed,  because  of  the 
use  of  the  protein-free  milk,  to  yield  any  quantitative  compari- 
sons of  the  biological  values  of  different  proteins.  But  extensive 
as  were  the  studies  discussed  in  this  chapter,  they  form  but  an 
incident  in  the  scientific  work  of  these  distinguished  investigators. 

The  effects  of  "protein-free  milk"  in  influencing  the  outcome 
of  numerous  experiments  has  been  dealt  with  somewhat  at  length 
because,  although  Osborne  and  Mendel  have  themselves  fur- 
nished data  which  clearly  indicate  the  part  which  this  substance 
played  in  their  work,  the  observations  were  never  definitely  cor- 
related with  their  earlier  work,  so  as  to  make  clear  their  changed 
views.  For  the  constantly  increasing  number  of  students  in  this 
field  it  seemed  desirable  to  offer  this  digest  of  one  phase  of  the 
literature  in  order  to  show  the  true  status  of  our  knowledge  in 
this  field. 

88.  Feces  of  Normally  Fed  Rats  Served  to  Complete  a  Diet 
of  Purified  Food  Substances. — In  some  of  these  early  experi- 
ments with  purified  food-stuffs,  Osborne  and  Mendel  (46)  added 
about  one  gram  per  week's  ration  of  dry  feces  of  normally  fed 
rats  to  their  experimental  diets.  Animals  which  were  rapidly 
declining  on  the  diets  of  purified  casein,  carbohydrate,  fat  (lard) 
and  a  salt  mixture,  were  markedly  benefited  by  the  addition  of 
one  per  cent  or  thereabouts  of  feces  of  normal  rats  to  their  diet. 
Some  were  able  to  grow  for  a  time  and  the  decline  of  all  was 
checked  by  this  addition.  To  explain  this  beneficial  effect  of 
the  inclusion  of  feces  in  the  diet,  several  possibilities  were  sug- 
gested and  discussed.  One  was  the  possibility  that  the  bacteria 
thus  introduced  into  the  alimentary  tract  were  able  to  elaborate 
substances  (e.  g.,  amino-acids)  necessary  to  complete  the  defects 
in  the  purified  protein  contained  in  the  diet.  This  seemed  in- 
adequate, because  with  other  purified  proteins  serving  as  the  sole 
source  of  amino-acids,  the  inclusion  of  feces  did  not  render  the 
diets  complete.  It  is  possible  that  the  body  cannot  thrive  unless 
the  alimentary  tract  harbors  a  flora  of  certain  types  of  micro- 
organisms. This  is  a  very  difficult  point  to  establish,  and  indeed, 
has  not  been  finally  settled.  There  was  also  the  possibility  that 
the  small  amount  of  protein  introduced  into  the  ration  with  the 
fecal  bacteria  might  be  sufficient  to  supplement  the  deficiencies 
of  the  protein  of  the  diet. 

In  the  light  of  later  developments  it  appears  that  the  rats 
which  were  confined  to  a  diet  of  purified  casein  and  otherwise 


78       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

of  purified  food  substances,  were  benefited  primarily  by  the 
inclusion  of  both  fat-soluble  A  and  water-soluble  B,  which  the 
feces  of  normal  rats  contained.  This  served  to  so  far  complete 
the  diet  that  the  animals  were  given  a  new  lease  of  life. 

89.  Stunting  of  Growth  Through  Inadequate  Protein  Does 
Not  Result  in  Loss  of  Capacity  to  Grow. — Osborne  and  Mendel 
fed  young  rats  on  diets  which  were  fairly  satisfactory  in  their 
composition  with  respect  to  all  factors  other  than  protein.  Their 
content  of  protein  was  below  the  amount  which  would  suffice 
for  the  support  of  growth.  The  animals  restricted  to  such  food 
supplies  remained  stunted  for  long  periods  and  yet  were  able, 
when  later  the  amount  of  protein  in  their  diets  were  increased, 
to  resume  growth  at  rates  which  the  experimenters  regarded  as 
faster  than  rats  ordinarily  grow  on  a  "normal"  diet.  From  these 
results  the  deduction  was  drawn  that  interruption  of  growth 
does  not  result  in  the  loss  of  the  capacity  to  grow  (46). 

This  generalization  is  too  sweeping.  It  is  true  that  rats  which 
are  stunted  by  means  of  protein  starvation  retain  for  long  pe- 
riods their  capacity  to  resume  growth  and  of  a  fairly  normal 
character,  the  form  of  the  grown  animal  being  more  or  less 
closely  similar  to  that  of  animals  whose  growth  to  adult  size 
has  been  uninterrupted.  McCollum  and  Simmonds  (46)  have 
found  that  rats  which  are  at  an  early  age  kept  upon  diets  in 
which  the  inorganic  content  is  unsatisfactory,  develop  abnormal 
forms,  and  become  permanently  stunted.  They  become  stocky, 
owing  to  failure  to  grow  in  length.  Such  animals  may  grow  to 
a  slight  extent  if  their  diet  is  later  made  satisfactory,  but  they 
always  remain  deformed.  Any  nutritive  regimen  which  will 
induce  rickets  will,  they  find,  markedly  interfere  with  subsequent 
growth,  when  later,  the  faults  in  the  diet  are  corrected. 

Animals,  whose  growth  has  been  suspended  by  depriving  them 
of  fat-soluble  A,  or  water-soluble  B,  are  able  to  resume  growth 
upon  the  inclusion  of  the  missing  complex  in  the  diet.  It  is  not 
possible,  however,  to  carry  animals  on  such  diets  for  long  pe- 
riods, because  of  the  disaster  which  inevitably  befalls  them. 

go.  Correlation  of  Nutritive  Value  of  Certain  Proteins  with 
Their  Lysin  Content. — Following  the  studies  which  led  Osborne 
and  Mendel  (37)  to  conclude  that  the  amino-acid  lysin  is  not 
necessary  for  maintenance  but  is  indispensable  for  growth,  Os- 
borne, Van  Slyke,  Leavenworth  and  Vinograd  (39)  made  a  very 
careful  analysis  of  the  principal  proteins  of  the  endosperm  of 
wheat,  maize  and  rice  kernels,  and  found  them  to  yield  1.58, 


NUTRITIVE  VALUE  OF  THE  PROTEINS  79 

0.97  and  4.26  per  cent,  respectively,  of  the  amino-acid  lysin. 
They  correlated  these  results  with  those  of  Thomas  (47)  secured 
in  brief  experiments  upon  himself  and  stated:  "It  is  rather 
striking  that  the  figures  for  the  utilizability  of  these  proteins 
correspond  so  closely  with  the  lysin  which  they  yield."  The 
three-day  type  of  digestion  trial  employed  by  Thomas,  in  which 
the  factor  of  growth  is  not  concerned,  can  be  scarcely  regarded 
as  affording  data  comparable  with  the  standards  required  in 
present-day  experimental  work. 

91.  Mistaken  Views  as  to  Unique  Importance  of  Lysin. — 
Buckner,  Nollau  and  Kastle  (48)  interpreted  Osborne  and  Men- 
del's data  as  showing  that  "lysin  is  primarily  responsible  for 
the  stimulation  of  growth."  They  apparently  regarded  the  plan- 
ning of  farm  rations  so  as  to  insure  a  sufficient  amount  of  this 
amino-acid,  as  one  of  the  specific  agricultural  problems  of  prac- 
tical importance.  These  investigators  fed  chicks  such  complex 
mixtures  as  wheat,  wheat  bran,  sunflower  seed,  hemp  seed  and 
skim  milk,  and  contrasted  the  growth  and  well-being  of  these 
chicks  with  others  restricted  to  barley,  rice,  hominy,  oats  and 
gluten  flour.  The  former  were  well  nourished  and  grew  in  a 
normal  manner  while  the  latter  were  stunted  and  miserable- 
looking  creatures.  Buckner,  Nollau  and  Kastle  interpreted  their 
results  as  being  due  to  "differences  in  the  amino-acid  content  of 
the  two  rations  and  in  all  probability  to  differences  in  the  lysin 
content." 

It  will  be  observed  that  the  poor  ration  used  in  the  feeding  of 
chicks  was  limited  to  cereal  grains  and  their  by-products.  One 
of  the  most  important  generalizations  that  can  be  made  as  the 
result  of  modern  nutrition  investigations  is  that  it  is  not  possible 
to  secure  a  diet  composed  entirely  of  seeds  of  plants  which 
will  promote  good  nutrition  over  any  considerable  period.  The 
diet  in  question  was,  it  is  true,  poor  in  the  amino-acid  lysin,  but 
its  mineral  content  was  deficient  in  certain  elements,  notably 
calcium,  phosphorus,  sodium  and  chlorin,  so  that  growth  was 
prevented  in  their  chicks,  even  if  the  proteins  had  been  of  better 
quality.  Furthermore,  this  diet  was  very  deficient  in  the  sub- 
stance fat-soluble  A,  without  which  prolonged  well-being  is  not 
possible.  It  contained  but  a  trace  of  the  anti-scorbutic  substance, 
which  may  have  been  of  some  importance  in  preventing  the  de- 
velopment of  the  chicks.  The  good  diet  on  the  other  hand  was 
composed  in  great  part  of  whole  seeds,  the  germ  of  which  im- 
proved the  quality  of  the  entire  mixture  of  vegetable  components 


80        THE  NEWER  KNOWLEDGE  OF  NUTRITION 

to  an  important  degree.  The  bran  was  important  as  a  source  of 
mineral  salts,  since  the  cortical  layer  of  seeds  is  especially  the 
region  in  which  these  occur  in  the  seed.  When  in  addition  to 
these  differences  between  the  two  diets,  the  presence  of  skim 
milk  in  the  successful  one  is  considered,  it  becomes  apparent 
that  the  two  diets  were  in  no  sense  comparable  even  in  regard  to 
factors  other  than  the  lysin  content.  It  can  confidently  be 
predicted  that  a  liberal  addition  of  lysin  to  their  poor  diet,  or 
indeed,  a  liberal  addition  of  all  the  essential  digestion  products 
of  protein  in  the  form  of  a  purified  protein  such  as  casein,  would 
not  have  changed  the  outcome  of  their  experiment. 

In  a  later  study  Osborne  and  Mendel  (49)  employed  maize 
gluten,  which  contains  about  1.0  per  cent  of  lysin,  supplemented 
with  "protein-free  milk"  sufficient  to  furnish  1.33  per  cent  of 
the  total  nitrogen  of  the  food  mixture,  as  the  source  of  protein 
for  growing  chicks.  They  compared  the  growth  obtained  with 
this  protein  mixture  with  that  obtained  with  rations  similar  in 
their  make-up  except  that  the  maize-gluten  nitrogen  and  "pro- 
tein-free milk"  nitrogen  was  supplemented  with  lactalbumin  or 
cottonseed  flour.  The  latter  supplements  are  known  to  be  rich 
in  lysin.  The  results  were  interpreted  as  confirming  the  con- 
clusions of  Buckner,  Nollau  and  Kastle  in  respect  to  the  effect 
of  foods  high  and  low  in  lysin  on  the  growth  of  chicks. 

From  the  standpoint  of  practical  nutrition  these  experimental 
studies  all  tended  to  focus  attention  upon  lysin  as  an  amino- 
acid  of  more  importance  than  other  indispensable  digestion  prod- 
ucts of  proteins,  because  of  the  assumption  that  it  is  relatively 
less  abundant  in  proteins  of  the  cereal  grains,  as  wheat,  maize, 
and  others. 

92.  Other  Amino- Acids  Than  Lysin  Are  as  Important 
as  Limiting  Factors  in  Protein  Nutrition  as  Is  Lysin. — This 
view  is  reflected  in  the  publications  of  Johns  and  his  co-workers 
(50) ,  who  have  emphasized  the  importance  of  discovering  among 
the  vegetable  foods  sources  of  proteins  rich  in  the  basic  amino- 
acids,  arginin,  histidin,  and  lysin,  and  especially  the  latter. 
The  logic  of  such  a  view  is  apparent,  and  is  amply  justified  by 
the  known  peculiarities  of  the  cereal  proteins  which  form  so  im- 
portant a  source  of  protein  in  the  nutrition  of  man  and  animal. 
These  peculiarities  have  been  brought  to  light  by  the  studies  of 
Osborne  and  Mendel,  who  have  shown  that  the  cereal  proteins 
are  especially  deficient  in  this  group  of  protein-building  units. 

The  view  that  any  generalization  regarding  the  cause  of  the 
low  biological  value  of  the  proteins  of  any  series  of  natural  foods 


NUTRITIVE  VALUE  OF  THE  PROTEINS  81 

is  possible,  is,  however,  without  foundation.  While  lysin  is  the 
limiting  factor  in  some  proteins  it  appears  not  to  be  more  fre- 
quently so  than  certain  other  amino-acids.  While  it  is  logical 
on  theoretical  grounds  to  combine  a  food  which  is  known  from 
the  results  of  chemical  studies  to  be  low  in  lysin,  or  any  other 
essential  amino-acid  with  another  food  especially  rich  in  such 
compound,  it  is  not  safe  to  place  much  confidence  in  the  results 
of  chemical  analysis  in  this  special  field  of  inquiry.  This  is  well 
illustrated  by  the  deductions  regarding  the  special  importance  of 
lysin  in  foods.  McCollum,  Simmonds  and  Pitz  (51)  have  shown 
that,  poor  as  are  the  proteins  of  the  maize  kernel  in  lysin,  this 
is  not  the  essential  amino-acid  which  is  present  in  smallest 
amount  in  proportion  to  the  amount  required  for  the  formation 
of  new  tissues  during  growth.  It  is  not  the  limiting  factor  in  de- 
termining the  value  of  the  maize  kernel  proteins.  It  would  not 
be  out  of  place  to  describe  the  procedure  which  established  these 
facts.  A  food  mixture  consisted  of  a  single  grain  so  supplemented 
with  inorganic  salts  and  butter  fat  as  to  be  satisfactory  for  the 
promotion  of  growth  and  prolonged  well-being,  except  that  the 
protein  was  too  low  in  amount  to  promote  growth  at  the  normal 
rate.  In  all  cases  the  diets  were  shown  to  be  made  highly  effi- 
cient for  growth  by  the  addition  of  a  purified  protein  alone,  when 
that  protein  was  casein  of  milk.  This  is  a  complete  protein  for 
the  nutrition  of  an  animal.  Rations  of  this  type  in  which  wheat, 
maize  or  oat  kernel  were  employed,  were  fed  to  young  rats,  and 
the  same  rations  supplemented  with  gelatin  or  zein  were  fed  to 
other  groups.  Zein,  the  most  abundant  protein  in  maize,  is  en- 
tirely lacking  in  trytophane  and  lysin,  whereas  gelatin  contains 
about  6  per  cent  of  lysin. 

Obviously,  if  lysin  were  the  limiting  amino-acid  in  each  of 
these  three  grains,  the  addition  of  gelatin  should  enhance  the 
value  of  the  proteins  in  all  cases  and  the  nutrition  of  the  animals 
should  be  correspondingly  improved.  The  addition  of  zein,  on 
the  other  hand,  should  not  lead  to  improvement.  The  outcome 
of  the  experiments  showed  that  zein  does  not  supplement  the 
proteins  of  the  wheat  or  maize  kernels,  but  does  improve  the 
proteins  of  the  oat  kernel  in  a  fairly  effective  manner.  Later 
investigations  have  caused  McCollum  and  Simmonds  to  question 
these  conclusions  so  far  as  the  oat  kernel  is  concerned.  Lysin 
may  possibly  be  the  limiting  factor  in  the  oat  kernel.  Hogan 
found  that  the  addition  of  lysin  and  tryptophane  to  maize  did 
not  enhance  the  nutritive  value  for  growth  of  swine  (52). 

Gelatin  supplements  the  proteins  of  both  the  wheat  and  oat 


82       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

kernel  in  a  very  efficient  manner,  but  does  not  enhance  the  value 
of  maize  kernel  proteins.  Since  gelatin  is  rich  in  lysin,  the  latter 
amino-acid  is  not  the  limiting  factor  in  the  proteins  of  the  maize. 
The  improvement  of  diets  containing  maize  gluten,  which  Os- 
borne  and  Mendel  (53)  observed  to  follow  the  introduction  of 
lactalbumin  or  cottonseed  proteins,  was  not  as  the  authors  be- 
lieved, the  result  of  the  addition  of  the  amino-acid  lysin. 

Some  further  deductions  are  possible  from  these  data.  These 
support  the  view,  but  do  not  prove  it  adequately,  that  lysin  is 
the  limiting  factor  in  wheat  kernel  proteins.  Since  gelatin  con- 
tains no  tryptophan  or  tyrosin  and  but  a  trace  of  cystin,  it 
suggests  that  none  of  these  three  amino-acids  are  the  ones  present 
in  minimal  amounts  in  wheat  or  oat  proteins. 

93.  Lactalbumin,  Although  Very  Rich  in  Lysin,  Is  an 
Incomplete  Protein. — A  further  illustration  of  the  fact  that  no 
generalization  can  be  made  on  the  basis  of  available  data,  con- 
cerning the  greater  importance  of  lysin  as  a  practical  problem 
in  nutrition,  than  certain  other  amino-acids,  is  afforded  by  the 
history  of  lactalbumin  studies.  These  have  already  been  de- 
scribed (p.  69).  Although  this  protein  is  one  of  the  richest 
known  in  lysin,  it  is  an  incomplete  protein  and  not  capable  of 
supporting  growth  unless  it  is  supplemented  with  a  source  of  a 
certain  missing  complex  or  complexes,  the  identity  of  which  has 
not  been  established. 

The  proteins  of  the  pea  or  bean  appear  from  chemical  data 
available,  to  be  more  closely  similar  in  their  constitution  to  the 
principal  animal-tissue  proteins  than  are  those  of  the  cereal 
grains,  and  they  are  certainly  more  abundant  sources  of  lysin. 
Their  dietary  values,  when  unsupplemented,  fall  far  short,  in- 
deed, of  those  of  the  cereals. 

Studies  like  those  that  have  been  described,  in  which  the  aim 
was  to  determine  the  possibility  of  supplying  the  needs  of  a 
growing  animal  for  protein-building  material  with  mixtures  of 
amino-acids  lacking  in  one  or  more  of  those  found  among  the 
digestion  products  of  most  proteins  are  extremely  valuable.  So 
are  studies  directed  toward  determining  the  nature  of  the  simple 
additions  of  amino-acids  which  make  complete  certain  proteins 
themselves  inadequate  as  a  source  of  nutriment  for  tissue  build- 
ing. It  is  these  types  of  investigations  which  bring  to  light  the 
synthetic  capacity  of  the  cells  and  contribute  to  an  understand- 
ing of  the  chemical  processes  normal  to  the  living  body  (54). 
The  problems  concerned  with  making  the  best  possible  use  of 


NUTRITIVE  VALUE  OF  THE  PROTEINS  83 

our  available  food-stuffs  demand,  among  other  things,  an  accurate 
understanding  of  the  biological  value  for  the  purposes  of  main- 
tenance and  growth,  of  the  protein  mixtures  contained  in  our 
foods.  These  problems  also  demand  a  knowledge  of  the  extent 
to  which  the  various  possible  combinations  of  foods  furnish  pro- 
tein mixtures  superior  to  those  of  the  individual  foods  when  the 
latter  constitute  the  sole  source  of  protein  in  the  diet  (55) . 

94.  Several  Other  Dietary  Factors  as  Important  as  Protein. 
— The  problem  of  practical  nutrition  is  really  much  broader  than 
this,  for  protein  constitutes  but  a  single  factor  of  importance  in 
nutrition.    The  content  of  the  essential  mineral  elements  in  the 
diet,  and  of  the  several  unidentified  factors,  the  absence  of  which 
leads  promptly  in  each  case  to  the  development  of  specific  patho- 
logical conditions,  are  of  equal  importance  from  the  standpoint 
of  the  well-being  of  the  body.    The  discovery  of  the  means  of 
making  the  nice  adjustments  in  a  quantitative  way  among  all 
the  factors  best  adapted  to  promote  optimum  development  and 
of  the  means  of  preserving  the  harmonious  rhythm  of  the  meta- 
bolic processes  in  the  best  possible  manner,  is  the  end  sought  by 
students  of  nutrition.     The  various  factors  mentioned  will  re- 
ceive attention  in  later  chapters. 

95.  An  Example  of  Faulty  Technic  in  Earlier  Experimental 
Studies  on  Nutritive  Worth  of  Protein. — McCollum  sought  to 
compare  in  growth  value  the  proteins  of  wheat,  maize  and  oat 
kernels  in  young  swine.    He  confined  the  animals  in  metabolism 
cages,  thus  making  possible  the  collection  of  the  excreta  during 
a  period  of  thirty  to  sixty  days,  during  which  the  animals  were 
fed  exclusively  on  a  single  grain  and  water  (56) .    From  the  rec- 
ord of  the  nitrogen  intake  and  output  of  the  animals  he  calculated 
the  amount  of  protein  of  the  food  which  was  converted  into  tissue 
proteins  for  new  growth.    The  results  indicated  that  the  protein 
mixture  contained  in  each  of  these  grains  can  be  utilized  to 
about  the  same  extent.     The  nitrogen  of  the  proteins  retained 
amounted  to  between  20  and  26  per  cent  of  the  amount  ingested 
in  all  cases.    The  per  cent  of  protein  in  the  food  did  not  appear 
to  influence  the  extent  of  utilization. 

It  is  now  certain  that  the  diet  used  in  these  experiments  was 
faulty,  in  respect  to  the  unsuit ability  of  the  mineral  content  of 
these  grains  for  the  maintenance  of  prolonged  normal  develop- 
ment. The  grains  are  deficient  in  fat-soluble  A,  and  are  almost 
entirely  lacking  in  the  anti-scorbutic  factor  water-soluble  C. 
The  pig  is  susceptible  to  scurvy,  and  the  lack  of  the  latter  was 


84       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

perhaps  a  factor  of  importance  in  determining  the  outcome  of 
the  experiments.  The  two  first  named  essentials  certainly  influ- 
enced the  result  of  these  studies,  for  the  rate  of  nitrogen  reten- 
tion fell  off  toward  the  end  of  the  period  of  observation. 

96.  A  Method  Which  Affords  a  Fairly  Accurate  Compari- 
son of  the  Values  of  Proteins. — The  type  of  experiment  which 
has  thrown  most  light  on  the  comparative  values  of  the  proteins 
of  different  foods  is  that  first  employed  by  McCollum  and  Davis 
(57)   for  showing  the  nature  of  the  dietary  deficiencies  of  the 
cereal  grains.     Their  method  has  since  been  applied  to  other 
important  seeds  and  to  leaves,  tubers  and  roots,  as  well  as  foods 
of  animal  origin  (58).    The  details  of  this  method  have  already 
been  described  (p.  27)  as  an  illustration  of  the  method  for  the 
biological  analysis  of  a  food-stuff.    It  consisted  in  feeding  to  one 
group  of  animals  a  natural  food  as  the  sole  source  of  nutriment, 
and  to  other  groups  of  animals  the  same  food  supplemented  with 
single  or  multiple  additions  of  purified  food-stuffs.    The  interpre- 
tation of  the  results  was  based  on  the  number  of  food  factors 
which  had  to  be  improved  before  growth  could  take  place,  and 
the  number  which,  when  improved  in  quality,  could  be  shown 
to  make  the  diet  of  better  quality,  as  revealed  by  fertility,  suc- 
cess in  rearing  young,  span  of  life,  and  general  well-being. 

The  results  showed  that  the  quality  of  the  proteins  of  the  seeds 
of  wheat,  maize,  oats,  rice,  pea,  bean,  flax,  millet,  and  kaffir  corn 
is  such  that,  when  fed  at  the  planes  of  intake  that  can  be  secured 
by  including  in  the  diet  as  much  of  the  seed  as  possible,  the 
optimum  condition  of  nutrition  is  not  attained,  even  though  all 
other  factors  in  the  diet  are  so  adjusted  as  to  be  fairly  satis- 
factory (59).  When  the  latter  conditions  are  fulfilled,  the  nu- 
trition of  the  animals  could  in  all  cases  be  improved  by  the  in- 
clusion in  the  diet  of  a  pure  protein  such  as  casein. 

97.  Every  Seed  Studied  Contains  Every  Amino-Acid  Nec- 
essary for  the  Nutrition  of  an  Animal. — These  studies  leave  no 
room  for  doubt  that  all  the  amino-acids  necessary  for  the  nutri- 
tion of  an  animal  are  contained  in  the  proteins  found  in  each  of 
these  foods.    Certain  of  these  are,  however,  present  in  such  lim- 
ited amounts  as  to  restrict  the  extent  to  which  the  remaining 
ones,  which  are  more  abundant,  can  be  utilized.     It  is  for  this 
reason  that  these  proteins  are  of  relatively  low  biological  value 
unless  supplemented  by  proteins  from  other  sources,  the  consti- 
tution of  which  is  such  as  to  make  good  their  deficiencies.    The 
proteins  of  the  cereal  grains  are  of  lower  value  than  are  those  of 


NUTRITIVE  VALUE  OF  THE  PROTEINS  85 

milk  and  eggs,  or  than  those  of  certain  mixtures  obtained  by 
combining  two  or  more  of  these  seeds.  • 

In  this  chapter  an  attempt  has  been  made  to  make  clear  the 
types  of  experiments  which  have  been  employed  for  the  study 
of  the  differences  in  the  nutritive  values  of  proteins  from  differ- 
ent sources,  and  to  determine  the  exact  nature  of  the  limiting 
deficiencies  of  each.  The  experimental  work  on  which  this  dis- 
cussion is  based  constitutes  the  most  confusing  phase  of  the  lit- 
erature relating  to  nutrition,  for  the  reason  that,  although  the 
specific  problems  which  have  been  investigated  have  in  great 
measure  been  cleared  up,  the  original  papers  have,  in  a  number 
of  cases,  failed  to  clearly  indicate  how  the  data  later  recorded 
modified  or  rendered  obsolete  earlier  observations  made  by  the 
investigators  themselves.  Frequent  references,  by  persons  who 
have  made  no  thorough  study  of  the  literature  to  supposedly 
proven  facts  which  were  later  disproved  by  other  experiments, 
have  convinced  the  author  that  an  interpretation  was  here  espe- 
cially desirable.  This  is  very  difficult  to  make  in  an  entirely 
clear  manner  without  exceeding  the  space  which  could  be  allotted 
to  it. 

98.  The  Nutritive  Value  of  a  Protein  Depends  on  Its 
Yields  of  the  Indispensable  Ammo-Acids. — The  work  reviewed 
clearly  establishes  that  the  nutritive  value  of  proteins  is  deter- 
mined by  their  yields  of  the  eighteen  or  more  amino-acids  which 
are  formed  on  digestion.  The  more  nearly  these  proportions 
correspond  to  the  content  of  amino-acids  in  the  tissues  of  the 
growing  animal,  the  more  effectively  can  food  proteins  be  trans- 
formed into  body  proteins.  There  are  surprising  differences  in 
the  biological  values  of  the  proteins  in  certain  of  our  more  im- 
portant foods.  These  will  be  discussed  more  fully  later. 

There  is  no  convincing  evidence  that  the  processes  of  mainte- 
nance, or  the  repair  of  tissue  waste,  are  of  a  lower  order  than 
those  of  growth,  and  that  the  needs  of  the  former  are  met  by  a 
list  of  amino-acids  which  would  be  lacking  in  certain  ones  which 
are  essential  for  the  latter.  Neither  has  it  been  possible  to 
demonstrate  that  through  the  agency  of  the  mammary  gland, 
amino-acids  (e.  g.,  lysin)  can  be  synthesized,  for  the  nutrition  of 
the  young  for  the  preservation  of  the  species,  whereas  this  can- 
not be  effected  for  the  preservation  of  the  individual.  The  evi- 
dence all  points  to  the  conclusion  that  the  transformation  of 
food  protein  into  milk  protein  is  governed  by  the  same  laws  as 
apply  to  growth. 


86       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

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Jour.  Biol.  Chem.,  1915,  xxiii,  231. 

29.  Osborne,  und  Mendel:    Beobachtunen  iiber  Wacshtum  bei  Futterungs- 

versuchen  mit  isolierten  Nahrungssubstanzen,  Zeit.  f.  physiol.  Chem., 
1912,  Ixxx,  367. 

30.  Osborne  and  Mendel:     Feeding  experiments  with  isolated  foodstuffs, 

Bull.  156,  Parts  1  and  2,  Pub.  of  the  Carnegie  Institution  of  Wash- 
ington, 1911. 

31.  Osborne,  and   Mendel:      The  comparative  nutritive   value   of  certain 

proteins  in  growth  and  problem  of  the  protein  minimum  for  main- 
tenance, Jour.  Biol.  Chem.,  1915,  xxii,  241. 

32.  Osborne,  and  Mendel:     The  role  of  the  vitamines  in  the  diet,  Jour. 

Biol.  Chem.,  1917,  xxxi,  149. 

33.  Babcock,  S.  M.,  and  Russell,  H.  L.:     Galactase,  the  proteolytic  enzyme 

peculiar  to  milk.  Its  properties  and  action  on  the  proteins  of  milk, 
Centralbl.  f.  Bacteriol.  u.  Parasitenk,  1900,  II,  6,  22,  45,  79. 

34.  Von    Freudenreich,    E.:     Galactase,    the    ferment    present    in    milk, 

Milchztg.  1900,  29,  245. 

35.  Osborne,  and  Mendel:     Feeding  experiments  with  isolated  food-stuffs, 

Bull.  156,  Parts  1  and  2,  Pub.  of  the  Carnegie  Inst.  of  Washington, 
1911. 

36.  Munk,  L:     Die  quantitative  Bestimmung  der  Eiweiss-  u.  Extraktiv- 

stoffe  in  Kuh-  und  Frauenmilch,  Virchow's  Arch.,  1893,  cxxxiv,  501. 

37.  Osborne,  and  Mendel:     The  role  of  gliadin  in  nutrition,  Jour.  Biol. 

Chem.,  1912,  xii,  473. 

38.  Osborne,  and  Mendel:  Amino-acids  in  nutrition  and  growth,  Ibid.,  1914, 

xvii,  325. 

39.  Osborne,  T.  B.,  Van  Slyke,  D.  D.,  Leavenworth,  C.  S.,  and  Vinograd, 

M.:  Some  products  of  hydrolysis  of  gliadin,  lactalbumin,  and  the 
protein  of  rice  kernel,  Jour.  Biol.  Chem.,  1915,  xxii,  259. 


88       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

40.  Osborne,  T.  B.:     Handbuch  der  biochemischen  Arbeitsmethoden,  E. 

Abderhalden,  1909. 

41.  Osborne,  and   Mendel:     The   comparative   nutritive  value  of  certain 

proteins  in  growth  and  the  problem  of  the  protein  minimum,  Jour. 
Biol.  Chem.,  1915,  xx,  351. 

42.  McCollum,  Simmonds,  and  Parsons:     The   dietary  properties  of  the 

pea,  Jour.  Biol.  Chem.,  1919,  xxxvii,  287. 

43.  Emmett,  A.  D.,  and  Luros,  G.  0.:     Is  lactalbumin  a  complete  protein 

for  growth?,  Jour.  Biol.  Chem.,  1919,  xxxviii,  147. 
Sure,  B.:     The  nutritive  value  of  lactalbumin;  crystin  and  tyrosin  as 
growth   limiting   factors   in  this   protein,  Jour.   Biol.   Chem.,    1920, 
xliii,  457. 

44.  Osborne,  T.  B.,  and  Wakeman,  A.:     Some  new  constituents  of  milk, 

Jour.  Biol.  Chem.,  1918,  xxxiii,  243. 

45.  Denis,  W.,  and  Minot,  A.  S.:     The  non-nitrogenous  constituents  of 

cow's  milk,  Jour.  Biol.  Chem.,  1919,  xxxviii,  453. 

46.  Kennedy,  C.:    The  forms  of  nitrogen  in  protein-free  milk,  Jour.  Amer. 

Chem.  Soc.,  1919,  xli,  388. 
Osborne,  and  Mendel:     The  contribution  of  bacteria  to  the  feces  after 

feeding  diets  free  from  indigestible  components,  Jour.  Biol.  Chem., 

1914,  xviii,  177. 
Osborne,  and  Mendel:     Pub.  156,  Carnegie  Inst.  of  Washington,  1911, 

Part  2,  61. 

Osborne,  and  Mendel:     Maintenance  experiments  with  isolated  pro- 
teins, Jour.  Biol.  Chem.,  1912,  xiii,  233. 
Osborne,  and  Mendel:     The  suppression  of  growth  and  the  capacity 

to  grow,  Jour.  Biol.  Chem.,  1914,  xviii,  95. 
Osborne,  and  Mendel:    The  resumption  of  growth  after  long  continued 

failure  to  grow,  Jour.  Biol.  Chem.,  1915,  xxiii,  439. 
Thompson,  H.  B.,  and   Mendel,   L.   B.:      An   experimental   study   of 

alternating    growth   and  suppressing   growth   in   the    albino    mouse 

with  special  reference  to  the  economy  of  food  consumption,  Amer. 

Jour,  of  Physiol.,  1918,  xlv,  431. 
McCollum,  and  Simmonds:     Unpublished  data. 

47.  Thomas,  K. :    Ueber  die  biologische  wertigkeit  der  Stickstoff-substanzen 

in  verschiedenen  Nahrungsmitteln,  Arch.  f.  Anat.  u.  Physiol.,  physiol. 
Abt.,  1909,  219. 

48.  Nollau,  E.  H.:    The  amino-acid  content  of  certain  commercial  feeding- 

stuffs  and  other  sources  of  protein,  Jour.  Biol.  Chem.,  1915,  xxi,  611. 

Buckner,   G.   D.,    Nollau,   E.   H.,   and   Kastle,   J.    H.:      Amer.   Jour. 

Physiol.,  1916,  xxxix,  162.    Kentucky  Agr.  Exp.  Sta.  Bull.,  1916,  197. 

49.  Osborne,  and  Mendel:     The  effect  of  the  amino-acid  content  of  the 

diet  on  the  growth  of  chicks,  Jour.  Biol.  Chem.,  1916,  xxvi,  293. 

50.  Johns,  C.  0.,  and  Jones,  D.  B.:     The  proteins  of  the  peanut — Arachis 

Hypogaea,  Jour.  Biol.  Chem.,  1917,  xxx,  33. 
Johns,  C.  O.,  and  Finks,  A.  J.:    Stitzolobin,  the  globulin  of  the  Chinese 

velvet  bean,  Stizolobium  niveum,  Ibid.,  1918,  xxxiv,  429. 
Johns,  C.  O.,  and  Chernoff,  L.  H.:     The  globulin  of  buckwheat,  Fago- 

pyrum,  Ibid.,  1918,  xxxiv,  439. 

51.  McCollum,  E.  V.,  Simmonds,  N.,  and  Pitz,  W.:     Is  lysin  the  limiting 

amino-acid  in  wheat,  maize  or  oats?    Jour.  Biol.  Chem.,  1916,  xxviii, 
483. 


NUTRITIVE  VALUE  OF  THE  PROTEINS  89 

52.  Hogan,  A.  G.:     The  nutritive  properties  of  corn,  Jour.  Biol.  Chem., 

1916,  xxvii,  193. 

53.  Osborne,  and   Mendel:      The  relative   value   of  certain  proteins   and 

protein    concentrates    as    supplements   to    corn    gluten,    Jour.    Biol. 
Chem.,  1917,  xxix,  69. 

54.  Osborne,  and   Mendel:      Amino-acids  in  nutrition  and  growth,  Jour. 

Biol.  Chem.,  1914,  xvii,  325. 

Willcock,  E.  G.,  and  Hopkins,  F.  G. :  The  importance  of  the  individual 
ammo-acids  in  metabolism.  Observations  on  the  effects  of  adding 
tryptophan  to  a  dietary  in  which  zein  is  the  sole  nitrogenous  con- 
stituent, Jour.  Physiol.,  1906-07,  xxxv,  88. 

Sure,  B.:  Amino-acids  in  nutrition:  1.  Studies  on  prolin:  Is  prolin 
a  growth-limiting  factor  in  arachin  (globulin  from  the  peanut)? 
Jour.  Biol.  Chem.,  1920,  xliii,  443. 

2.  The  nutritive  value  of  lactalbumin:  cystin  and  tyrosin  as  growth- 
limiting  factors  in  that  protein,  Ibid.,  xliii,  457. 

3.  Is  prolin  a  growth-limiting  factor  in  the  protein  of  peas  (Vicia 
sativa)  ?     What  nucleus   in   zein  is   responsible   for  supplementing 
these  proteins?,  Ibid.,  1921,  xlvi,  443. 

Osborne,  and  Mendel:  The  comparative  nutritive  value  of  certain 
proteins  in  growth  and  the  problem  of  the  protein  minimum,  Jour. 
Biol.  Chem.,  1915,  xx,  351. 

Osborne,  and  Mendel:  The  amino-acid  minimum  for  maintenance  and 
growth  as  exemplified  by  further  experiments  with  lysin  and 
tryptophan,  Ibid.,  1916,  xxv,  1. 

Johns,  and  Finks:  The  role  of  cystin  in  nutrition  as  exemplified  by 
experiments  with  the  proteins  of  the  navy  bean,  Jour.  Biol.  Chem., 
1920,  xli,  379. 

Mitchell,  H.  EL:  Feeding  experiments  on  the  substitution  of  protein 
by  definite  mixtures  of  isolated  amino-acids,  Jour.  Biol.  Chem., 
1916,  xxvi,  231. 

Lewis,  H.  B.,  and  Root,  L.  E.:  Amino-acid  synthesis  in  the  animal 
organism — Can  norleucin  replace  lysin  for  the  nutritive  require- 
ments of  the  rat?,  Jour.  Biol.  Chem.,  1920,  xliii,  79. 

55.  Richardson,  A.  E.,  and  Green,  H.  S.:     Nutrition  investigations  upon 

cottonseed   meal,   Jour.   Biol.   Chem.,   1916,   xxv,   307;    Ibid.,   1917, 

xxx,  243. 
Osborne,  and  Mendel:     Nutritive  properties  of  the  maize  kernel,  Ibid., 

1914,  xvii,  1. 
Hart,  E.  B.,  and  Humphrey,  G.  C.:    The  relation  of  the  quality  of  the 

proteins  to  milk  production,  Ibid.,  1915,  xxi,  239. 
McCollum,  Simmonds,  and  Pitz:     Dietary  deficiencies  of  the  maize 

kernel,  Ibid.,  1916-17,  xxviii,  153. 
Osborne,  and  Mendel:     The  use  of  cottonseed  as  food,  Ibid.,   1917, 

xxix,  289. 
McCollum,  Simmonds,  and  Pitz :    The  dietary  deficiencies  of  the  white 

bean,  Ibid.,  1917,  521. 

McCollum,  Simmonds,  and  Pitz:  The  supplementary  dietary  relation- 
ship between  leaf  and  seed  as  contrasted  with  combinations  of  seed 

with  seed,  Ibid.,  1917,  xxx,  13. 
McCollum,  and  Simmonds:     The   dietary  properties   of  mixtures   of 

maize  kernel  and  bean,  Ibid.,  1917,  xxxii,  209. 


90       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Daniels,  A.  L.,  and  Loughlin,  R.:     Feeding  experiments  with  peanuts, 

Ibid.,  1918,  xxxiii,  295. 
McCollum,  and  Simmonds:     The  causes  of  failure  of  mixture  of  seeds 

to  promote  growth  in  young  animals,  Ibid.,  1918,  xxxiii,  303. 
Steenbock,  H.,  Kent,  H.  E.,  and  Gross,  E.  G.:     The  dietary  qualities 

of  barley,  Ibid.,  1918,  xxxv,  61. 
McCollum,  Simmonds,  and  Parsons:     Supplementary  protein  values  in 

foods,  iii,  Jour.  Biol.  Chem.,  1921,  xlvii,  111-247. 

56.  McCollum:     The  values  of  the  proteins  of  cereal  grains  and  of  milk 

for  growth  in  the  pig,  and  the  influence   of  the  plane  of  protein 
intake  on  growth,  Jour.  Biol.  Chem.,  1914,  xlx,  323. 
Hart,  and  McCollum:     Influence  on  growth  of  rations  restricted  to  the 
corn  or  wheat  grain,  Ibid.,  1914,  xix,  373. 

57.  McCollum,  and  Davis:     The  nature  of  the  dietary  deficiencies  of  the 

rice  kernel,  Ibid.,  1915,  xxiii,  181. 

58.  McCollum,  Simmonds,  and  Pitz:  The  nature  of  the  dietary  deficiencies 

of  the  wheat  embryo,  Ibid.,  1916,  xxv,  105. 

The  nature  of  the  dietary  deficiencies  of  the  oat  kernel,  Ibid.,  1917, 
xxix,  341. 

The  dietary  deficiencies  of  the  white  bean,  Ibid.,  1917,  xxix,  521. 
Osborne,  and  Mendel:     Nutritive  factors  in  plant  tissues;  the  protein 

factor  in  the  seeds  of  cereals,  Jour.  Biol.  Chem.,  1918,  xxxiv,  521. 
Osborne,  and  Mendel:     Nutritive  factors  in  animal  tissues,  Ibid.,  1917, 

xxxii,  309;  Ibid.,  1918,  xxxiv,  17. 
Osborne,  and  Mendel:     Nutritive  value  of  the  wheat  kernel  and  its 

milling  products,  Ibid.,  1919,  xxxvii,  557. 
Sugiura,  K.,  and  Benedict,  S.  R.:     The  nutritive  value  of  the  banana, 

Jour.  Biol.  Chem.,  1918,  xxxvi,  171. 
McCollum,  Simmonds,  and  Parsons:     The  dietary  properties  of  the 

potato,  Jour.  Biol.  Chem.,  1918,  xxxvi,  197. 

59.  Osborne,   and    Mendel:      Nutritive    properties    of   the    maize    kernel, 

Jour.  Biol.  Chem.,  1914,  xviii,  1. 

Hogan,  A.  G.:    The  nutritive  properties  of  corn,  Ibid.,  1916,  xxvii,  193. 
Johns,  C.  0.,  and  Brewster,  J.  F.:     Kafirin,  an  alcohol-soluble  protein 

from  kafir,  Jour.  Biol.  Chem.,  1916-17,  xviii,  59. 
McCollum,  Simmonds,  and  Pitz:     Dietary  deficiencies  of  the   maize 

kernel,  Jour.  Biol.  Chem.,  1916-17,  xxviii,  153. 
McCollum,  Simmonds,  and  Pitz:     The  effects  of  feeding  the  proteins 

of  the  wheat  kernel  at  different  planes  of  intake,  Jour.  Biol.  Chem., 

1916-17,  xviii,  211. 
McCollum,  Simmonds,  and  Pitz:    Is  lysin  the  limiting  amino-acid  in 

the  proteins  of  the  wheat,  maize  or  oat  kernel?,  Jour.  Biol.  Chem., 

1916-17,  xxviii,  483. 
Daniels,  A.  L.,  and  Nichols,  N.  B.:     The  nutritive  value  of  the  soy 

bean,  Jour.  Biol.  Chem.,  1917,  xxxii,  91. 
Osborne,  and  Mendel:     The  use  of  the  soy  bean  as  food,  Jour.  Biol. 

Chem.,  1917,  xxxii,  369. 
Hogan:     The  nutritive  properties  of  kafirin,  Jour.  Biol.  Chem.,  1918, 

xxxiii,  151. 


CHAPTER  V 

PECULIARITIES  OF  COMPOSITION  OF  PROTEINS 
FROM  VARIOUS  SOURCES 

99.  Certain  Ammo-Acids  Are  Demonstrated  to  Be  In- 
dispensable for  Animal  Nutrition. — In  Chapter  IV  a  brief  ac- 
count was  given  of  the  experimental  studies  which  established 
the  fact  that  the  nutritive  value  of  a  protein  depends  upon  the 
number  and  amounts  of  the  amino-acids  it  yields  on  artificial 
hydrolysis  or  on  digestion.  It  was  shown  that  a  protein  such  as 
gelatin,  which  is  lacking  in  the  amino-acids,  tyrosin,  cystin  and 
tryptophan,  or  that  a  protein  such  as  zein  of  maize  kernel,  which 
is  lacking  in  lysin,  is  incomplete  for  all  physiological  purposes 
since  is  cannot  supply  all  the  "building  stones"  necessary  for  the 
construction  of  body  proteins.  No  matter  how  much  of  such  a 
protein  is  present  in  a  diet,  which  may  be  entirely  adequate  with 
respect  to  all  other  food  factors,  nutritive  disaster  will  speedily 
overtake  the  animal  confined  to  it.  The  nutritive  value  of  a  pro- 
tein or  mixture  of  proteins  depends  upon  the  presence  in  its 
molecules  of  all  the  essential  amino-acids,  and  upon  the  extent 
to  which  their  proportions  correspond  to  those  existing  in  the 
body  proteins  they  are  to  be  transformed  into.  It  is  obvious, 
therefore,  that  mixtures  of  proteins  unlike  in  their  constitution 
may  yield  amounts  of  the  several  amino-acids  which  will  tend 
to  make  them  more  efficient  than  either  or  any  individual  protein 
in  the  mixture.  One  protein  may  supplement  the  deficiency  of 
the  other.  On  these  facts  was  based  a  criticism  of  certain  of 
the  experimental  work  designed  to  yield  data  showing  in  a  quan- 
titative way,  the  comparative  values  of  different  purified  pro- 
teins. These  purified  proteins  were  not  fed  as  the  sole  source 
of  nitrogen  (amino-acids)  but  were  supplemented  with  fairly 
liberal  additions  of  amino-acids  in  the  "protein-free  milk"  or 
yeast  which  was  included  in  the  diet. 

In  order  to  illustrate  further  the  differences  in  the  constitution 
of  individual  proteins  from  different  sources  a  few  tables  are 
presented  which  contain  in  summarized  form  the  best  analytical 
data  which  it  has  been  possible  to  obtain  by  chemical  methods. 

91 


92      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Table  I  shows  the  composition  of  a  series  of  animal  and  vegetable 
proteins  and  the  sources  of  origin.  On  the  left  side  is  shown  the 
percentage  composition  of  each  in  carbon,  hydrogen,  nitrogen, 
sulphur  and  oxygen,  which  are  the  only  elements  entering  into 
the  formation  of  the  simple  proteins.  These  elements  are  desig- 
nated by  the  symbols,  C,  H,  N,  S  and  0  respectively.  On  the 
right-hand  side  in  their  respective  columns  are  tabulated  the 
number  of  atoms  of  each  of  these  elements  which  a  single 
molecule  of  the  protein  is  believed  to  contain,  and  in  the  column 
headed  "Molecular  Weight"  are  the  numbers  which  indicate  ap- 
proximately the  weight  of  a  single  protein  molecule  as  compared 
with  an  atom  of  hydrogen  which  is  taken  as  unity. 

100.  Elementary   Composition   of   all   Proteins   Is  of   the 
Same  Order. — The  most  interesting  information  to  be  gained 
from  this  table,  is  the  remarkable  similarity  of  the  proteins 
from  various  sources  in  respect  to  their  content  of  carbon,  hydro- 
gen and  oxygen,  and  their  relatively  wide  differences  in  nitrogen 
and  sulphur  content.    Ovalbumin  of  the  hen's  egg  contains  but 
15.51  per  cent  of  nitrogen,  whereas  amandin  from  the  almond 
contains  19.32  per  cent.    Legumin  from  the  bean  contains  but 
0.385  per  cent  of  sulphur,  while  serumalbumin  from  human  blood 
contains  2.25  per  cent  of  this  element,  or  nearly  six  times  as 
much  for  equal  weights  of  the  two  substances. 

101.  The  Hausmann  Method  of  Analysis  of  Proteins  and 
the  Data  Obtained. — In  Table  I  is  shown  data  regarding  the 
constitution  of  different  proteins  as  revealed  by  another  method 
of  analysis  known  as  the  Hausmann  method.     There  is  in  every 
protein  a  complex  which,  when  boiled  for  a  few  hours  with  mod- 
erately  strong  mineral   acids,  yields   ammonia.     In   the   table 
the  per  cent  of  the  total  nitrogen  of  the  protein  which  is  con- 
vertible into  ammonia  is  tabulated  in  the  first  column  under 
NH3-N.    There  are  three  diamino-acids  derived  from  proteins, 
which  are  sharply  differentiated  from  all  the  others  by  their 
basic  character,  that  is,  they  have  an  alkaline  reaction  when  in 
solution.    They  can  be  precipitated  together  by  means  of  phos- 
photungstic  acid,  and  thus  separated  sharply  from  all  the  other 
constituents  of  the  protein  molecule.     The  remaining  amino- 
acids  formed  on  hydrolysis  or  digestion  of  proteins  are  collec- 
tively designated  as  mono-amino  acids.    The  yields  of  these  are 
tabulated  in  the  third  column.    When  proteins  are  heated  with 
acids  as  is  necessary  in  the  method  of  analysis  under  discussion, 
there  is  always  formed  a  certain  amount  of  black,  insoluble 


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94       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

nitrogenous  substance  called  humin.  It  has  been  shown  that 
most  of  this  comes  from  the  decomposition  of  a  single  compound 
called  tryptophan,  one  of  the  mono-amino  acids.  Some  pro- 
teins are  entirely  lacking  in  tryptophan.  An  example  of  such  a 
protein  is  zein  of  the  maize  kernel.  In  the  column  headed  "Total 
N,"  is  given  the  per  cent  of  nitrogen  in  the  samples  of  the  pro- 
teins employed  in  the  analyses. 

An  inspection  of  this  table  shows  that  the  amount  of  nitrogen 
in  the  protein  molecule  which  is  convertible  into  ammonia  under 
the  conditions  of  the  analysis,  varies  from  as  low  as  6.46  per  cent 
in  legumelin  of  the  pea  or  bean  to  as  high  as  23.78  per  cent  in 
gliadin  of  wheat.  In  contrast  with  the  proteins  of  animal  origin, 
it  will  be  noticed  that  many  of  the  proteins  of  vegetable  origin 
contain  two  or  three  times  and  a  few  more  than  four  times  the 
amount  of  nitrogen  in  this  special  ammonia-yielding  complex. 
This  is  one  of  the  types  of  data  which,  as  early  as  1905,  clearly 
showed  that  the  proteins  differ  to  a  great  extent  in  their  constitu- 
tion, and  that  food  proteins  are  in  most  cases  quite  unlike  the 
proteins  which  compose  the  muscles  and  organs  of  the  body. 

The  method  of  analysis  by  means  of  which  the  data  in  Table  II 
were  secured,  is  not  a  very  searching  one,  and  fails  to  yield  as 
detailed  information  as  is  desired  for  physiological  reasoning. 
For  this  purpose  the  differences  in  the  yields  of  the  diamino- 
acids  (bases)  in  different  proteins  do  not,  except  in  a  few  in- 
stances, contrast  markedly  with  each  other.  In  the  case  of 
glutenin,  gliadin,  hordein  and  zein,  the  principal  proteins  of  the 
wheat,  barley,  and  maize  kernels,  the  content  of  the  basic  amino- 
acids  falls  far  below  that  present  in  any  of  the  animal  proteins. 
As  will  be  seen  from  the  next  table  to  be  considered,  there  is 
more  to  be  learned  about  this  fraction  of  the  protein  molecule 
than  the  above  data  reveal.  There  are  three  substances  in  this 
group,  the  names  of  which  are  arginin,  histidin  and  lysin.  Dif- 
ferent proteins  show  marked  variation  in  the  content  of  one  or 
another  of  them. 

1 02.  The  Content  of  Arginin,  Histidin  and  Lysin  in  Indi- 
vidual Proteins. — Table  III  (p.  96)  contains  analytical  data  ob- 
tained by  a  refined  method  for  the  estimation  in  proteins  of  the 
three  diamino-acids,  arginin,  histidin  and  lysin.  This  method 
was  devised  by  Kossel.  In  skilful  hands  it  yields  very  accurate 
results.  It  will  be  noted  that  the  histidin  content  of  plant  pro- 
teins varies  much  less  than  does  that  of  either  arginin  or  lysin. 
Yet  the  extreme  values  for  this  constituent  of  the  protein  molecule 


PECULIARITIES  OF  COMPOSITION  OF  PROTEINS      95 


TABLE  II 

DISTRIBUTION  OF  NITROGEN  IN  PROTEINS* 
TOTAL  N  =  100 


NH3 

N 

Basic 
Amino 
Acids 

N 

Mono- 
Amino 
Acids 

N 

Humin 

N 

Total 

N 

Vegetable  Proteins: 
Conalbumin  (egg  white) 
Phaseolin    (bean)    

7.51 
1074 

25.82 
2450 

65.11 

6285 

1.61 
1  79 

16.11 
1620 

Glycinin  (pea) 

1209 

2263 

6458 

68 

1745 

Legumelin  (pea,  bean)  .  . 
Leucosin  (wheat)  
Olutenin  (wheat)  

6.46 
6.85 

18  86 

23.06 
20.67 
11  72 

68.12 
69.87 
6832 

2.36 
2.54 
1  09 

16.09 
16.93 
1749 

Oliadin  (rye)  

2378 

549 

7027 

79 

1766 

Hordein  (barley)  

2330 

447 

6996 

1  33 

1721 

Zcin  (maize) 

1Q  41 

0  f)Q 

77  56 

qq 

ifi  13 

Globulin  (wheat) 

7  72 

Q7  14 

53  39 

i  K.O 

1C  QQ 

Globulin  (coca  nut)  
Globulin  (squash  seed)  .  . 
Globulin  (cotton  seed)  .  . 
Edestin  (hemp  seed)  
Excelsin  (para  nut)  
Corylin  (hazel  nut)  
Amandin  (almond)  

7.35 
6.91 
10.30 
10.08 
8.87 
11.57 
16  04 

32.79 
32.25 
30.63 
31.70 
31.47 
30.26 
21  84 

59.09 
59.64 
59.06 
57.83 
59.94 
56.31 
6008 

.75 
1.18 

.64 

.92 
.89 
89 

18.48 
18.51 
18.64 
18.64 
19.30 
19.00 
1900 

Globulin  (castor  bean)  .  . 
Corylin  (walnut)  . 

10.45 
Q44 

30.08 

00  71 

58.66 
fi1  OQ 

.64 
7Q 

18.75 

ICC/1 

Congluten  (a)  (lupine).. 
Congluten  (b)  (lupine).. 
L/egumin  (pea)  

11.84 
14.55 
Q40 

29.05 

28.17 

00  GO 

58.00 
56.56 
6027 

1.00 
.76 
Q4 

17.90 
18.21 
17  07 

Globulin  (flaxseed)  
Vicilin  (pea  bean) 

10.82 

10  40 

25.81 

97  7fi 

62.06 
fiftfiO 

1.18 

1   00 

18.48 

1711 

Vignin  (pea) 

U07 

OK  qq 

fiOfifi 

i  4* 

17  OK 

Globulin  (sunflower  seed) 
Stizolobin  (Velvet  bean) 
Arachin  (Peanut)  

Animal  Proteins: 
Vitellin    (egg  yolk)  
Casein  (cow's  milk)  
Ovalbumin  (egg)  

13.83 
10.51 
11.10 

7.67 
10.30 

C  «4 

22.98 
27.96 
27.13 

28.56 
22.84 
21  27 

62.00 
60.06 
60.50 

62.41 
66.00 

AC  21 

1.29 
1.36 
1.20 

1.35 
1.34 

187 

18.58 
16.40 

18.28 

1658 
15.62 
1551 

Chicken  muscle  

745 

29  98 

KG  CPJ 

243 

1609 

Halibut  muscle 

fi  7fl 

30  18 

6073 

237 

1640 

Scallop  muscle 

633 

2651 

6481 

234 

17.05 

Beef  muscle  

5.50 

27.32 

64.52 

2.65 

16.18 

*  Compiled  from  the  papers  of  T.  B.  Osborne  and  of  C.  0.  Johns, 


96      THE  NEWER  KNOWLEDGE  OF  NUTRITION 


TABLE  III 

CONTENT  OF  ARGININ,  HISTIDIN  AND  LYSIN  IN  PROTEINS.* 


Histidin 


Arginin 


Lysin 


Vegetable  Proteins: 

Globulin    (Buckwheat)    0.88 

Globulin   (Squash  seed)    2.42 

Excelsin    (Para   nut)    2.50 

Edestin   (Hemp  seed)    2.19 

Globulin  (Cotton  seed)   3.46 

Stizolobin  (Velvet  bean)    3.81 

Globulin   (Castor  bean)    2.74 

Amandin   (Almond)    1.87 

Legumin    (Pea)    1.69 

Legumin   (Vetch)    2.94 

Conglutin  A    (Lupine)    2.51 

Vicilin    (Pea)    2.17 

Glycinin   (Soy  bean)    2.10 

Vignin  (Cow  pea)   3.08 

Glutelin  (Maize)    3.00 

Leucosin    (Wheat)    2.83 

Legumelin  (Pea)    2.27 

Legumelin   (Soy  bean)    2.04 

Phaseolin  (Kidney  bean)   .......  2.62 

Glutenin  (Wheat)   1.76 

Gliadin  (Wheat)    0.58 

Gliadin    (Rye)    0.39 

Hordein   (Barley)    1.28 

Zein   (Maize)    0.82 

Animal  Proteins: 

Ovovitellin  (Egg  yolk)    1.90 

Beef   muscle    2.66 

Scallop  adductor  muscle  2.02 

Chicken  muscle   2.47 

Halibut   muscle    2.55 

Conalbumin  (Egg  white)   2.17 

Ovalbumin  (Egg  white)    1.71 

Casein  (Cow  milk)   2.50 

Lactalbumin    .  2.06 


23.67 

14.44 

14.29 

14.17 

13.51 

14.13 

13.19 

12.16 

11.73 

11.06 

10.93 

8.91 

7.69 

7.20 

7.06 

5.94 

5.45 

5.35 

4.87 

4.72 

3.16 

2.22 

2.16 

1.35 

7.46 
7.47 
7.38 
6.50 
6.34 
5.07 
4.91 
3.81 
3.23 


8.61 
1.99 
1.64 
1.65 
2.06 
10.02 
1.54 
0.72 
4.98 
3.70 
2.73 
5.40 
3.39 
4.31 
2.93 
2.75 
3.03 
4.91 
4.58 
1.92 
1.33 


0.00 

4.81 
7.59 
5.77 
7.24 
7.45 
6.43 
3.76 
5.95 
9.16 


*This  table  is  compiled  from  various  sources,  especially  the  papers  of 
Osborne  and  of  Johns. 

range  from  3.81  per  cent  in  stizolobin,  a  globulin  from  the  velvet 
bean,  to  0.39  per  cent  in  gliadin  from  rye.  The  content  of 
arginin  in  different  proteins  varies  in  a  surprising  degree.  Thus 
a  globulin  of  buckwheat  yields  23  per  cent  arginin,  whereas  zein 
of  the  maize  kernel  contains  but  1.35  per  cent.  Among  the 
vegetable  proteins  the  yield  of  lysin  is  generally  very  low  in  com- 


PECULIARITIES  OF  COMPOSITION  OF  PROTEINS      97 

parison  to  that  obtained  from  the  proteins  of  animal  tissues. 
The  extreme  limits  of  the  yield  of  lysin  in  plant  proteins  range 
from  10.2  per  cent  in  the  globulin  of  the  velvet  bean  to  complete 
absence  in  zein  of  maize. 

A  comparison  of  the  relative  amounts  of  these  three  digestion 
products  in  proteins  of  vegetable  with  those  of  animal  origin 
reveals  at  once  a  remarkable  fact.  While  the  amount  of  histidin 
is  of  the  same  order  in  the  two  classes,  arginin  is  found  in  many 
proteins  of  seeds  in  quantities  greatly  in  excess  of  any  of  the 
proteins  of  animal  tissues.  The  only  vegetable  proteins  yet 
studied  which  exceed,  in  their  content  of  lysin,  the  muscle  pro- 
teins of  animals,  are  those  of  the  velvet  bean  and  buckwheat  (1). 

TABLE  IV 
PER  CENT  OP  GLUTAMIC  ACID  YIELDED  BY  PROTEINS.* 

Vegetable  Proteins: 

Gliadin    (Wheat)    42.98  per  cent. 

Gliadin  (Rye)    37.80 

Hordein  (Barley)    43.19 

Zein  (Maize)    26.17 

Leucosin   (Wheat)    5.72 

Glutenin  (Wheat) 23.40 

Amandin  (Almond)    23.14 

Edestin  (Hemp  seed)    14.00 

Corylin  (Hazel  nut)    17.94 

Phaseolin   (Bean)    12.33 

Vignin  (Pea,  bean)    16.30 

Legumin   (Vetch)    16.48 

Glycinin  (Soy  bean) 19.46 

Conglutin  (Yellow  lupine)    : 30.05 

Animal  Proteins: 

Casein  (Cow  milk)    ,. 10.77 

Ovalbumin    (Egg) 9.01 

Conalbumin    (Egg)     7.00 

Vitellin  (Egg  yolk)    12.95 

Serum  albumin  (Horse)   7.70 

Serum  globulin   (Horse)    8.50 

Halibut  muscle    10.13 

Chicken   muscle    16.48 

Scallop    muscle    14.88 

Dog  tissues,  entire  body 14.00 

Rabbit  tissues,  entire   body 14.14 

Hen  tissues,  entire  body .- 12.02 

*  Compiled  data  from  various  sources,  especially  the  papers  of  T.  B. 
Osborne  and  E.  Abderhalden. 


98       THE  NEWER  KNOWLEDGE  OF  NUTRITION 

It  was  the  marked  deficiency  of  most  of  the  vegetable  proteins 
in  lysin  in  contrast  to  the  animal  proteins  that  led  Osborne  and 
Mendel  and  others  to  believe  at  one  time  that  this  amino-acid 
was  frequently  the  limiting  factor  which  determined  the  nutritive 
value  of  food  proteins.  The  investigations  relating  to  this  phase 
of  nutrition  have  been  described  in  the  preceding  chapter. 

103.  Variation  in  the  Glutamic  Acid  Content  of  Proteins. 
— Table  IV  shows  the  composition  of  a  number  of  proteins  of 
animal  and  vegetable  origin  with  respect  to  glutamic  acid.  This 
amino-acid  is  a  never-failing  component  of  all  vegetable  proteins 
and  of  all  animal  proteins  except  the  protamins,  which  have 
been  found  in  the  spermatozoa  of  fish.  It  will  be  seen  that  this 
hydrolytic  product  is  frequently  much  more  abundant  in  veg- 
etable proteins  than  in  animal  tissues  or  in  egg  or  milk  proteins. 

With  these  data  available,  it  is  easy  to  understand  why  food 
proteins  show  great  variations  in  nutritive  value,  for  this  depends 
upon  the  efficiency  with  which  they  can  be  transformed  during 
growth,  or  in  the  course  of  the  repair  of  tissue  waste  into  tissue 
proteins.  They  also  reveal  the  logic  of  taking  a  mixture  of  pro- 
teins in  the  food,  since  by  this  means  there  is  a  probability  that 
the  deficiencies  of  one  protein  may  be  in  some  measure  corrected 
by  another  which  may  yield  liberal  amounts  of  those  amino-acids 
it  lacks  wholly  or  in  part.  Since  in  practice  both  in  human  nutri- 
tion and  animal  nutrition  several  proteins  are  always  taken  to- 
gether, either  when  vegetable  or  animal  tissues  are  used  as  food 
or  when  the  by-products  of  manufacture  are  employed  as  sup- 
plements to  naturally  occurring  foods,  it  is  of  great  economic 
importance  to  discover  what  foods  contain  proteins  which  possess 
high  supplementary  values.  Protein  is  the  most  expensive  com- 
ponent of  foods  or  feeding-stuffs,  and  agricultural  economics  can 
be  greatly  advanced  by  scientific  discovery  in  this  field.  In 
human  nutrition  the  element  of  economy,  in  ordinary  times, 
enters  less  as  a  factor  than  physiological  well-being,  but  it  would 
appear  that  it  is  no  less  important  here  that  a  protein  supply 
of  high  biological  value  be  provided  in  the  diet.  It  seems  logical 
to  prefer  to  serve  the  needs  of  the  body  by  providing  it  with 
the  optimal  amount  of  such  proteins  as  can  be  utilized  very 
effectively  rather  than  to  require  it  to  digest  and  assimilate  an 
excessive  amount  of  proteins  of  low  value.  In  this  connection 
it  must  be  remembered  that  the  moiety  of  amino-acids  which 
cannot  be  properly  matched  with  each  other  so  as  to  form  the 
necessary  structures  have  to  be  promptly  destroyed  and  their 


PECULIARITIES  OF  COMPOSITION  OF  PROTEINS      99 

degradation  products  eliminated  as  waste.  This  would  impose 
an  unnecessary  burden  on  the  organs  concerned  with  the  metab- 
olism of  the  nitrogenous  components  of  food. 

104.  Conditions  Necessary  for  the  Comparison  of  Proteins 
by  Feeding  Experiments. — In  order  to  study  the  effectiveness 
with  which  the  proteins  of  one  food  supplement  those  of  another 
it  is  essential  that  diets  be  planned  so  as  to  be  highly  satisfactory 
with  respect  to  all  other  factors  besides  protein.    The  natures 
of  the  deficiencies  of  all  the  foods  studied  must  first  be  well 
understood,  so  that  any  mixtures  employed  in  experiments  de- 
signed to  reveal  the  biological  values  of  combinations  of  proteins 
may  be  supplemented  with  respect  to  inorganic  salts,  the  essen- 
tial vitamins,  etc.    Under  such   considerations  the  success  or 
failure  of  growth,  reproduction  or  other  function  in  the  animals 
will  turn  solely  on  the  quality  of  the  proteins  of  the  experimental 
diet.    In  Chapter  VI  the  dietary  properties  of  many  of  the  more 
important  of  our  foods  are  given  in  detail,  so  that  it  is  now  pos- 
sible to  appreciate  the  method  employed  in  the  study  of  the  pro- 
tein values  of  combinations  of  these  articles  of  diet. 

105.  Methods  of  Procedure  for  Comparing  the  Biological 
Values  of  Individual  Proteins. — Several  lines  of  procedure  offer 
prospects   of  successful   comparison   of  the  relative   biological 
values  of  mixtures  of  proteins.     One  is  to  feed  a  series  of  groups 
of  young  and  growing  animals  a  diet  similarly  constituted  and 
deriving  its  protein  from  the  same  source,  but  with  the  per  cent 
of  protein  adjusted  in  the  series  from  very  low  to  very  high  levels. 
From  the  rate  of  growth  of  the  animals  an  idea  can  be  gained 
as  to  the  least  amount  of  protein  from  the  sources  studied,  which 
just  suffices  to  maintain  animals  without  growth  and  to  induce 
growth  at  subnormal  rates,  or  at  the  maximum  rate. 

Another  method  of  investigation  is  to  utilize  female  animals 
nursing  litters  of  young.  By  adopting  a  standard  size  for  the 
litters,  and  by  observing  the  success  with  which  the  mothers 
induce  growth  in  their  young  when  the  diet  contains  different 
percentages  of  protein  but  is  otherwise  of  uniform  composition, 
an  approximately  quantitative  comparison  of  the  values  of  the 
proteins  from  different  sources  can  be  made. 

Osborne  and  Mendel  (2)  made  attempts,  in  their  studies  with 
isolated  proteins,  to  determine  their  relative  values  by  observing 
the  growth  of  animals  which  ate  the  same  amount  of  food  in  the 
same  number  of  days  and  gained  the  same  amount  in  weight. 
The  protein  factor  was  the  only  variable.  It  is  very  difficult  to 


100     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

conduct  experiments  in  this  manner,  and  Osborne  and  Mendel  (3) 
attempted  to  develop  another  method  by  restricting  the  protein 
so  that  it  became  the  factor  which  determined  the  rate  of  growth, 
and  then  attempted  to  discover  the  concentration  of  protein  in  the 
diet  promoting  the  greatest  gain  of  body  weight  relative  to  the 
protein  ingested.  To  accomplish  this  result  they  supplied  the 
experimental  animals  with  foods  containing  different  percentages 
of  the  same  protein.  Using  this  method  they  secured  data  which 
is  illustrated  by  the  following  table: 


Protein 

Initial 
Body 

Protein 
in 

Intak 
Gram  c 

e  Per 
>/  Gain. 

Gain  Per 
Gram  of 

Gain  Per 
Gram  of 

Weight. 
Grams. 

Food. 
Per  Cent. 

Food. 
Grams. 

Protein. 
Grams. 

Food. 

Protein. 
Grams. 

Lactalbumin   .  . 

62 
61 
73 
67 

16.2 

u 
il 
(I 

3.3 
2.6 
3.4 

3.8 

0.52 
0.42 
0.54 
0.60 

0.31 
0.39 
0.30 
0.27 

1.93 
2.41 
1.86 
1.67 

Average 

33 

052 

032 

197 

Lactalbumin   .  . 

71 
63 

10.3 

u 

3.6 

4.0 

0.37 
0.42 

0.28 
055 

2.74 
2.41 

Average  

3.8 

0.40 

0.27 

2.58 

Lactalbumin   .  . 

64 

70 

7.9 
(i 

4.0 
4.5 

0.31 
0.35 

0.25 
0.22 

3.18 
2.83 

Average  

4.3 

0.33 

0.24 

3.01 

Lactalbumin   .  . 

66 
67 

6.2 

u 

6.3 
6.0 

0.39 
0.37 

0.16 
0.17 

2.58 
2.69 

Average  

6.2 

0.38 

0.17 

2.64 

Lactalbumin   .  . 

63 
63 

4.9 
u 

8.6 

8.9 

0.42 
0.43 

0.12 
0.11 

2.40 
2.32 

Average  

8.8 

0.43 

0.12 

2.36 

Lactalbumin    .  . 

68 
67 

3.3 

« 

18.7 
24.6 

0.62 
0.82 

0.05 
0.04 

1.63 
1.23 

Average  

21.7 

0.72 

0.05 

1.43 

In  a  similar  study  in  which  casein  was  the  protein  used,  the 
protein  intake  was  in  most  cases  higher  than  in  the  lactalbumin 


PECULIARITIES  OF  COMPOSITION  OF  PROTEINS    101 

experiments.     For  the  sake  of  comparison  the  results  are  given 
below  in  condensed  form. 

Protein    .................................................  ...  Casein 

Per  cent  in  food  ............................................  17.4 

Weights  of  experimental  animals  .............................  58-76  grams 

f  Food....  3.1;  4.0;  3.0;  3.5;  3.9;  3.1;  3.5;  3.0;  3.4. 

...    I  Average,  3.4. 

Intake  per  gram  of  gam^  Protein    0  54  .  070;  053;  06].  06g.  053;  061; 

I  0.52;  0.59.    Average,  0.59. 

Protein  .....................................................  Casein 

Per  cent  in  food  ............................................  14.7 

Weights  of  experimental  animals  ............................  64-67  grams 

,       .    fFood....4.1;  3.5;  3.0.    Average,  3.5. 
Intake  per  gram  of  gain^^    Q  6Q  .  Q51;  Q44     Ayerage> 


Protein  .....................................................  Casein 

Per  cent  in  food  ............................................  12.0 

Weights  of  experimental  animals  ............................  63-69  grams 

T  ,  ,          /Food  ____  4.2;  3.5;  3.5.    Average,  3.7. 

Intake  per  gram  of  gainjp^^  >a50;   Q>42;   ^     Averag6j  ^ 


Protein Casein 

Per  cent  in  food 9.3 

Weights  of  experimental  animals 64-65  grams 

'Food.... 8.9;  6.4;  7.4.    Average,  7.6. 

!;  0.59;  0.68.    Average,  0.70. 


Intake  per  gram  of  gain{|^;  ; 


1 06.     Individual  Variation  in  Rate  of  Growth  of  Rats. — 

From  the  data  given  it  will  be  seen  that  under  the  same  experi- 
mental conditions  and  on  the  same  diet  the  variation  in  gain  of 
body  weight  amounted  to  as  much  as  75  per  cent  and  the  gains 
per  gram  of  protein  ingested  varied  as  much  as  10  to  30  per  cent 
in  different  animals.  The  most  plausible  explanation  of  the 
lack  of  uniformity  in  the  rate  of  growth  in  their  animals  was 
that  their  stock  included  animals  of  very  low  vigor  as  well  as 
those  of  greater  vitality.  There  was  thus  introduced  into  their 
interpretation  an  averaging  of  growth  in  animals  not  able  to 
make  efficient  use  of  food  for  growth  with  growth  in  others  in 
which  growth  impetus  and  synthetic  powers  were  greater.  // 
we  desire  to  learn  the  extent  to  which  a  food  protein  during 
growth  can  be  converted  into  body  proteins  it  would  be  more 
logical  to  accept  only  the  greatest  gain  observed  in  any  animal, 
discarding  all  other  results,  rather  than  to  average  the  gains 
made  by  good  and  poor  ones.  From  their  data  Osborne  and 
Mendel  estimate  that  the  gain  of  weight  per  gram  of  protein  eaten 
during  a  period  of  eight  weeks  was  for  lactalbumin  2.34  and  for 


102     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

casein  1.70  grams.  In  three  experiments  with  casein  fed  at  12.0 
per  cent  of  the  food  mixture,  the  animals  made  an  average  gain 
of  2.25  grams  per  gram  of  casein  consumed.  One  animal  attained 
a  gain  of  2.39  grams  and  another  of  1.99  grams.  Their  results 
are  not  very  convincing  as  proof  of  the  superiority  of  this  method 
as  a  measure  of  the  relative  biological  value  of  proteins.  In 
interpreting  the  value  of  the  data  in  the  tables  in  which  lactal- 
bumin  and  casein  are  compared,  it  should  be  borne  in  mind 
that  neither  protein  was  fed  as  the  sole  source  of  nitrogen,  but 
that  it  was  supplemented  with  the  nitrogen  of  28.2  parts  of  pro- 
tein-free milk.  It  has  already  been  pointed  out  that  lactalbumin 
is  actually  an  incomplete  protein  and  is  incapable  of  inducing 
any  growth  whatever  unless  its  deficiencies  are  made  good  by 
some  other  source  of  amino-acids.  The  extent  to  which  the  pro- 
tein-free milk  nitrogen  supplemented  the  proteins  in  these  experi- 
ments was  very  great.  Thus  in  the  diets  where  16  per  cent  of 
lactalbumin  was  included,  8.3  per  cent  of  the  total  nitrogen  of 
the  diet  came  from  protein- free  milk.  In  the  diets  which  con- 
tained 10.0  per  cent,  6.2  per  cent  and  3.3  per  cent  of  lactal- 
bumin, the  per  cent  of  the  total  nitrogen  derived  from  protein- 
free  milk  was  13.4  per  cent,  22.4  per  cent  and  41.0  per  cent, 
respectively.  The  recorded  data  of  Osborne  and  Mendel  do  not 
in  any  sense  represent  a  comparison  of  the  biological  values  of 
casein  and  lactalbumin,  and  actually  give  a  wholly  false  im- 
pression. It  has  already  been  pointed  out  that  they  were  forced 
to  revise  because  of  the  faulty  technique  in  their  experiments 
their  views  concerning  the  values  of  several  of  the  proteins  which 
they  studied  most  extensively  (4). 

107.  Conditions  Under  Which  Energy  and  Protein  Are 
Used  Most  Economically  by  Growing  Animals. — The  data  of 
Osborne  and  Mendel  discussed  above,  have  an  interest  quite 
apart  from  their  worth  as  quantitative  comparisons  of  the  rela- 
tive values  of  proteins.  They  support  the  view  that  "Economy 
of  food  can  be  effected  only  by  supplying  the  young  animal  with 
as  much  as  it  will  eat;  economy  of  protein  only  by  reducing 
the  nutritive  ratio  below  that  at  which  the  normal  rate  of  growth 
can  be  maintained."  This  principle  appears  to  be  established, 
but  it  is  quite  another  matter  to  determine  whether  or  not 
economy  of  protein  utilization  obtained  by  the  means  just  men- 
tioned, makes  for  physiological  well-being.  The  studies  of  Mc- 
Collum  and  Simmonds,  to  be  described  later,  point  to  the  desir- 
ability, from  the  standpoint  of  the  long  maintenance  of  vigor, 


PECULIARITIES  OF  COMPOSITION  OF  PROTEINS     103 

of  a  liberal  supply  of  protein  in  a  diet  which  is  otherwise  satis- 
factorily constituted  with  respect  to  all  other  factors. 

1 08.  The  Method  of  McCollum,  Simmonds  and  Parsons  for 
Comparing  the  Nutritive  Values  of  Proteins. — A  procedure  in- 
troduced by  McCollum,  Simmonds  and  Parsons    (5)    for  the 
study  of  the  relative  values  of  different  proteins,  or  for  the  sup- 
plementary values  of  proteins  from  different  sources,  involves 
feeding  a  series  of  groups  of  animals  on  a  series  of  diets  which 
are  of  uniformly  excellent  quality  with  respect  to  all  factors  ex- 
cept quality  of  protein.    The  diets  are  all  made  to  contain  9  per 
cent,  of  total  protein,  which  may  be  derived  from  a  single  food 
or  from  two  or  more  sources  as  stated  above.     On  such  diets 
young  rats  are  observed  during  the  entire  growth  period  and 
thereafter  up  to  the  time  when  pronounced  development  of  senile 
characters  are  noted.    The  groups  contain  animals  of  both  sexes, 
and  the  fertility  and  infant  mortality  are  carefully  observed. 
The  behavior  of  the  animals,  especially  with  respect  to  a  ten- 
dency to  destroy  their  new-born  young  when  the  protein  supply 
is  unsatisfactory,  is  also  carefully  recorded. 

This  method  was  the  outgrowth  of  considerable  experience  in 
searching  for  the  most  satisfactory  procedure  for  making  a  com- 
parison of  the  effectiveness  of  different  foods  as  protein  supple- 
ments for  one  another.  McCollum  and  his  co-workers  had  con- 
ducted numerous  experiments  in  feeding  animals  diets  contain- 
ing different  percentages  of  protein,  and  otherwise  enhanced  so 
as  to  make  them  of  good  quality,  and  had  made  an  effort  to  study 
the  relative  values  of  purified  proteins  and  of  .the  mixtures  of 
proteins  contained  in  individual  natural  foods,  both  for  growth 
and  for  the  replacement  of  the  nitrogen  lost  through  endogenous 
or  tissue  metabolism  (6).  In  the  early  studies  too  little  was 
known  about  supplementing  factors  other  than  protein.  None 
of  these  results  are  to  be  regarded  as  very  satisfactory  for  the 
reason  that  factors  other  than  protein  in  the  experimental  diets 
employed,  were  not  always  satisfactorily  improved  to  make  the 
results  turn  entirely  upon  the  quality  of  the  proteins  of  the  food. 

109.  Importance  of   Quantitative   Records  of  Food   Con- 
sumption.— Many  of  these  studies  were  severely  criticized  by 
Osborne  and  Mendel  because,  when  rats  were  employed  as  ex- 
perimental animals  no  accurate  records  were  kept  to  show  the 
exact   amounts  of  food   consumed  by   each   individual.    They 
pointed  to  the  great  differences  in  amount  of  food  eaten  by  dif- 
ferent rats  as  evidence  that  there  must,  in  this  kind  of  work, 


104     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

be  a  correlation  between  food  consumption  and  growth.  Osborne 
and  Mendel  were  able  by  using  large  amounts  of  fat  to  convert 
their  foods  into  a  paste,  which  could  be  placed  in  a  glass  tube 
provided  with  a  rod  acting  as  a  plunger.  Each  rat  was  kept 
in  an  individual  cage.  Food  was  from  time  to  time  expelled 
from  this  device  into  the  feeding  dish.  Employing  this  device 
in  all  their  experiments  they  were  able  to  furnish  figures  for 
food  consumption. 

McCollum  was  not  able  to  secure  a  quantitative  record  of  food 
intake  in  his  animals  (rats)  until  about  1915,  for  he  and  his 
co-workers  employed  diets  in  the  form  of  finely  ground  powders. 
These  consisted  of  either  purified  food  substances,  or  of  natural 
foods  with  certain  additions  of  salts,  fats,  etc. 

no.  A  Feeding  Device  for  Measuring  the  Food  Consump- 
tion of  the  Rat  Fed  Dry  Powdered  Food. — Their  plan  did  not 
admit  of  the  inclusion  of  large  amounts  of  fat  in  their  food  mix- 
tures, because  this  procedure  diluted  so  much  the  mineral  content, 
protein  content,  etc.,  of  any  natural  food  under  investigation,  that 
it  made  it  impossible  to  feed  sufficient  amounts  of  grains,  legume 
seeds,  etc.,  to  give  an  accurate  picture  of  their  dietary  properties. 
It  was  imperative,  for  their  purposes  that  rats  should  be  fed  with 
dry  powders.  A  device  was  finally  designed  which  left  little  to 
be  desired  for  the  quantitative  feeding  of  such  powders.  This 
consists  of  a  tin  pie  plate  suspended  from  the  roof  of  the  cage 
by  means  of  three  wires  which  are  attached  to  the  rim  of  the 
pan  so  that  they  occupy  the  position  at  the  angles  of  an  equi- 
lateral triangle.  These  wires  are  brought  together  like  the  tepee 
lodgepoles,  being  connected  with  a  ring  by  means  of  a  small 
link  for  each  wire.  A  wire  is  passed  through  perforations  in  the 
rim  of  the  pan  so  as  to  cross  it  at  a  line,  the  center  of  which  lies 
half  the  diameter  of  a  pint  tin  cup  from  the  center  of  the  pie 
pan.  This  wire  is  bent  so  as  to  form  a  circle  which  circumscribes 
the  center  of  the  pan.  The  circle  is  just  large  enough  to  admit 
of  the  insertion  of  a  pint  tin  cup  without  a  handle.  The  feeding 
cup  is  thus  held  securely  in  the  center  of  the  pan.  Inserted  in  the 
mouth  of  the  tin  cup  is  a  cover  so  made  as  to  fit  firmly  into  the 
cup  like  the  lid  of  a  dinner  pail.  The  top  of  this  cover  is  shaped 
much  like  the  top  of  a  cuspidor,  being  funnel-shaped  and  having 
a  hole  in  the  center,  through  which  the  rats  can  secure  the  pow- 
dered food.  In  order  to  minimize  the  chances  of  scattering  food, 
the  cover  is  made  about  double  the  diameter  of  the  tin  cup,  so 
that  it  forms  a  large  funnel  which  tends  to  return  the  traces  of 


PECULIARITIES  OF  COMPOSITION  OF  PROTEINS    105 

powdered  food  to  the  cup  should  any  be  removed  and  not  eaten 
by  the  rat.  If  this  device  is  not  filled  more  than  half  full,  it  is 
impossible  for  a  rat  to  scratch  any  of  the  food  from  the  cup.  It 
must  eat  through  the  hole  in  the  center.  The  size  of  this  hole 
may  be  gauged,  if  desired,  to  the  size  of  the  rats  used  in  experi- 
ment. 

With  this  device  McCollum  and  Simmonds  found  it  easy  to 
secure  records  of  food  intake  which  certainly  are  accurate  to 
within  1  per  cent.  Since  they  did  not  keep  their  animals  in 
individual  cages,  but  in  groups  of  four  to  eight  or  ten  in  one 
large  cage,  most  of  their  records  showed  the  food  consumption  of 
the  group  and  not  of  any  one  individual.  This  practice  was 
followed  because  of  the  great  increase  which  it  made  possible 
in  the  number  of  animals  which  could  be  kept  under  observation, 
thus  making  feasible  the  conduct  of  a  much  larger  number  of 
experiments. 

Experiments  with  feeding  various  sources  of  proteins  at  dif- 
ferent percentages  of  the  food  mixtures  brought  to  light  the  fact 
that  there  are  few  sources  of  proteins  among  our  ordinary  foods 
sufficiently  high  in  quality  that  a  diet  containing  but  9  per  cent 
of  protein,  and  otherwise  satisfactory  will  be  adequate  for  the 
promotion  of  growth  at  the  maximum  rate  and  to  the  full  adult 
size,  and  for  the  maintenance  to  an  advanced  age  of  a  high  health 
standard  in  the  rats  confined  to  it.  Only  such  proteins  will,  when 
fed  at  this  plane  of  intake,  serve  to  maintain  the  vitality  of 
rats  at  a  point  where  their  fertility  will  be  high,  and  the  nursing 
of  their  litters  satisfactory. 

in.  Method  of  Expressing  the  Relative  Nutritive  Values 
of  Proteins. — Results  characteristic  of  excellent  nutrition  can  be 
secured  with  diets  planned  as  just  described,  in  which  the  pro- 
teins are  derived  solely  from  milk,  kidney,  or  a  mixture  of  cer- 
tain seeds,  notably  of  rye  and  flaxseed  oil  meal.  So  far  as  experi- 
ence has  progressed,  however,  such  effects  cannot  come  from 
restricting  rats  to  any  diet  containing  less  than  9  per  cent  of 
protein  from  any  source.  McCollum,  Simmonds  and  Parsons  (7) 
felt  justified  in  classing  as  excellent,  any  protein  or  protein  mix- 
ture which  would  support  nearly  optimal  nutrition  over  periods 
approximating  two-thirds  or  more  of  the  normal  span  of  life  of 
the  rat,  when  fed  in  amount  corresponding  to  9  per  cent  of  the 
food  mixture.  Instead  of  trying  as  Osborne  and  Mendel  had 
done,  to  establish  absolute  values  for  the  proteins,  they  under- 
took only  to  compare  any  protein  or  mixture  of  proteins  with 


106     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

some  protein  which,  according  to  the  definition  just  given,  would 
be  classed  as  excellent,  or  in  other  words,  about  as  good  as  any 
proteins  known  from  the  nutritive  standpoint. 

In  order  to  do  this,  McCollum,  Simmonds  and  Parsons  simply 
confined  groups  of  four  to  six  rats  in  a  cage  24x24x20  inches 
in  dimensions,  screened  on  all  sides,  or  on  three  sides  with  wire 
cloth  of  one-quarter  inch  mesh.  The  food  records  always  showed 
the  amount  consumed  in  the  group.  Note  was  kept  of  the  num- 
ber of  times,  with  dates,  when  the  standard  quantity  of  one  kilo- 
gram of  food  was  prepared.  The  animals  were  not  able  to  dis- 
pose of  their  food  otherwise  than  through  eating.  It  was  believed 
that  a  more  detailed  record  of  individual  food  consumption  would 
add  little  if  any  value  to  the  results  or  make  their  interpretation 
more  significant.  Since  Osborne  and  Mendel  have  repeatedly  em- 
phasized their  belief  that  feeding  studies  of  this  nature  fail  of 
their  purpose  unless  accurate  food  consumption  records  are  kept, 
it  is  incumbent  upon  McCollum  and  his  co-workers  to  defend 
their  system  against  this  criticism. 

112.  Changing  Food  Consumption  with  Growth. — When  a 
young  animal  is  growing  there  is  a  constantly  increasing  need 
for  food,  and  a  progressive  increase  in  consumption  is  observed. 
If  two  animals  are  fed  diets  which  are  alike  except  for  their  pro- 
tein content,  or  in  the  nature  of  their  proteins,  one  may  grow 
because  the  protein  of  its  food  is  well  constituted,  while  the  other 
may  fail  because  the  protein  in  its  food  is  deficient  in  some  re- 
spect.    Comparison  of  food  intake  and  consequently  of  protein 
consumption  is  not  practicable  in  these  animals  since  the  dif- 
ference in  size  is  becoming  constantly  more  pronounced.    Os- 
borne and  Mendel  have  made  an  elaborate  study  of  food  con- 
sumption in  rats  under  different  dietary  restrictions,  and  their 
data  are  of  great  interest  in  connection  with  the  present  ques- 
tion (8). 

They  found  that  rats  growing  well  on  a  diet  containing  9  per 
cent  of  casein  when  a  small  amount  of  cystin  was  added,  fre- 
quently ate  no  more  food  in  terms  of  calories,  and  ingested  no 
more  protein  than  did  rats  which  were  growing  no  better  on 
even  larger  percentages  of  casein  without  the  addition  of  cystin. 
They  concluded  in  this  instance:  "It  thus  appears  that  a  marked 
deficiency  in  any  essential  ingredient  of  the  diet  does  not  lead  to 
a  corresponding  compensatory  increase  in  food  intake." 

113.  Appetite  as  a  Factor  Governing  Food  Consumption. — 
Their  study  of  the  role  of  appetite  in  regulating  food  consump- 


PECULIARITIES  OF  COMPOSITION  OF  PROTEINS    107 

tion  has  led  them  to  state:  "The  experience  which  we  have  gained 
in  measuring  the  food  eaten  by  many  rats  at  all  periods  of  their 
growth  has  given  us  the  conviction  that  the  intake  of  the  indi- 
vidual is  determined  in  large  measure  by  the  energy  requirement 
at  any  given  period"  (8)  (p.  358).  To  quote  from  page  359  of 
the  same  paper,  "At  any  rate  the  animals  do  not  consume  propor- 
tionately more  of  the  artificial  ration  because  it  happens  to  be 
decidedly  poor  in  protein;  but  roughly  speaking,  they  appear  to 
limit  their  feeding  to  the  amount  of  food  yielding  approximately 
the  requisite  energy."  This  view  is  in  accord  with  that  of 
Rubner  (9),  who  found  that  food  which  a  dog  will  eagerly  devour 
when  in  a  room  at  the  temperature  of  0°  C.,  he  will  in  part  refuse 
when  the  temperature  is  raised  to  33°,  under  which  conditions, 
his  energy  requirements  are  much  lower. 

In  a  later  publication  Osborne  and  Mendel  (10)  showed  the 
food  consumption  of  rats  fed  diets  containing  varied  amounts  of 
fat.  Since  fat  has  about  double  the  energy  value  of  protein 
or  carbohydrate,  much  smaller  amounts  of  the  fat-rich  diets 
would  furnish  the  required  amount  of  energy  needed  than  would 
be  necessary  with  the  fat-poor  diets.  In  all  cases  food  consump- 
tion was  found  to  be  regulated  by  energy  needs  and  was  com- 
parable in  animals  on  diets  of  similar  calorific  value. 

It  is  only  necessary  to  point  out  that  McCollum  and  his  co- 
workers  have  throughout  their  studies  employed  diets  low  in 
fats,  and  very  much  alike  in  their  energy  values.  Food  intake 
should  have  been,  therefore,  according  to  Osborne  and  Mendel's 
experience,  entirely  comparable.  Numerous  records  obtained 
in  recent  years  in  the  laboratory  at  Johns  Hopkins  University 
have  shown  clearly  that  this  is  the  case.  Quoting  again  from 
the  paper  of  Osborne  and  Mendel  from  which  extracts  have  al- 
ready been  presented  (p.  523),  "McCollum  does  not  state  the 
amount  of  food  which  his  experimental  rats  ate;  but  if  we 
assume  that  they  ate  quantities  of  the  type  of  food  which  he 
employed  in  amounts  approximately  equal  to  those  eaten  by 
rats  in  our  experiments  on  foods  of  corresponding  calorific  value, 
the  difference  between  the  results  of  his  experiments  and  ours 
disappear."  The  force  of  their  repeated  criticisms  of  the  work 
of  McCollum  and  his  co-workers  largely  vanish  with  the  record- 
ing of  this  comment. 

Owing  to  faults  in  the  technic  employed  in  earlier  experiments, 
we  find  ourselves  to-day  with  extremely  little  information  con- 
cerning the  manner  and  extent  to  which  any  purified  proteins 


108     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

supplement  one  another,  and  to  the  manner  and  extent  to  which 
they  are  by  combination  mutually  enhanced  in  biological  value. 
On  the  other  hand  we  have  a  very  considerable  amount  of  ac- 
curate knowledge  concerning  the  supplementary  dietary  rela- 
tions among  certain  of  our  most  important  food-stuffs.  To  these 
supplementary  relations  we  will  now  turn  our  attention. 

114.  Supplementary    Values    of    Proteins   from    Different 
Sources. — Employing  the  method  described  above,  in  which  an 
effort  is  made  to  determine  the  extent  to  which  any  protein  or 
mixture  of  proteins  falls  short  of  the  best  quality  yet  observed 
in  proteins,  McCollum,  Simmonds  and  Parsons  made  an  elabo- 
rate study  of  a  long  list  of  simple  combinations  of  two  natural 
foods,  supplemented  with  respect  to  all  factors  other  than  pro- 
tein.   In  all  cases  the  protein  constituted  9  per  cent  of  the  diet 
since  this  plane  of  intake  is  a  critical  one  even  when  the  protein 
is  of  good  quality.    The  life  histories  of  experimental  rats  con- 
fined to  such  diets  show  clearly  whether  the  protein  content  of 
any  diet  made  on  the  plan  described  should  be  classed  as  poor, 
good  or  excellent.    The  details  of  the  extent  to  which  the  ani- 
mals are  able  to  grow,  perform  the  functions  of  reproduction, 
and  retain  the  characteristics  of  youth,  enable  one  to  differentiate 
between  shades  of  quality  in  this  moiety  of  the  diet,  to  a  degree 
of  refinement  not  equalled  by  any  other  method  of  study. 

Employing  this  method,  McCollum,  Simmonds  and  Parsons 
studied  the  relative  values  of  the  proteins  of  kidney,  liver  and 
muscle  of  the  ox  as  the  sole  source  of  protein.  Of  these  kidney 
is  easily  shown  to  be  superior  to  the  other  two  tissues.  As 
sources  of  amino-acids  liver  is  second,  and  muscle  third  in  value. 

In  Chart  4  are  presented  curves  snowing  the  extent  to  which 
young  rats  are  able  to  grow  when  confined  to  diets  which  were 
comparable  in  all  respects  and  the  protein  came  from  a  single 
source.  With  the  exception  of  the  diet  in  which  milk  proteins 
were  supplied  as  the  sole  source  of  nitrogen,  the  diets  described 
in  this  chart  derived  their  protein  from  a  single  seed,  either  a 
cereal  grain  or  a  legume  seed. 

115.  Proteins  of  Extraordinary  Value. — Kidney,  liver  and 
milk  proteins  stand  out  as  a  group  of  foods  containing  proteins 
of  unusual  value.    Among  the  cereal  grains,  wheat  easily  stands 
first  in  the  quality  of  its  proteins.    There  is  little  reason  to  at- 
tempt to  place  rye,  maize,  barley,  flaxseed  oil  meal,  rolled  oats 
and  kaffir  corn  in  their  order  of  values  as  the  sole  source  of  nitro- 
gen in  the  diet.    All  that  can  safely  be  said  is  that  barley  and 
rye  appear  to  be  slightly  better  than  the  other  seeds  named. 


IJIiii 


109 


KNOWLEDGE  OF  NUTRITION 


Kidney  proteins  alone,  when  fed  at  9  per  cent  of  the  food 
mixture,  appear  to  give  excellent  nutrition,  and  the  fact  that  it  is 
not  entirely  adequate  appears  only  in  the  falling  off  of  the  fer- 
tility of  the  animals  to  decidedly  below  the  maximum.  As  is  the 
rule  with  families  of  rats  confined  through  several  generations 
to  a  monotonous  diet,  which  is  faulty  in  a  slight  degree,  each 
succeeding  generation  is  smaller  when  its  growth  is  completed, 
and  in  a  few  generations,  indeed,  the  strain  dies  out. 

116.  Proteins  of  Cereal  Grains  Do  Not  Supplement  Each 
Other.  —  Without  exception  it  has  been  found  that  two  cereal 
grains  fail  to  supplement  very  well  the  protein  deficiencies  of 
one  another  and  accordingly  animals  do  little  or  no  better  when 
fed  9  per  cent  of  protein  derived  from  two  cereals  than  they  do 
when  confined  to  one.  There  are,  however,  some  remarkable 
instances  of  effective  supplementing  between  certain  cereal  grains 
and  certain  of  the  legume  seeds.  Conspicuous  among  these  suc- 
cessful combinations  is  wheat  and  pea.  When  fed  with  all  neces- 
sary additions  other  than  protein,  a  group  of  young  rats  grew 
to  the  full  adult  size  and  the  females  were  very  fertile.  There 
was  a  slight  decrease  in  size  in  succeeding  generations,  but  the 
females  of  the  third  generation  were  still  vigorous  enough  to 
produce  and  rear  young.  In  this  diet  the  wheat  furnished  two- 
thirds  and  the  peas,  one-third  of  the  total  proteins. 

Maize  kernel  and  pea,  fed  in  combination  parallel  to  the 
wheat  and  pea  ration  just  mentioned,  proved  almost  a  failure 
for  the  nutrition  of  the  rat.  The  young  animals  confined  to  this 
diet,  the  only  fault  of  which  lay  in  its  protein  moiety,  failed  to 
grow  as  rapidly  as  they  should,  and  were  permanently  under- 
sized. Fertility  in  the  females  was  very  low,  and  the  second 
generation  of  this  family  after  weaning  increased  very  slowly 
in  weight.  See  Charts  5  and  6. 

It  would  take  us  too  far  afield  to  comment  in  detail  upon  the 
relative  merits  of  all  the  numerous  protein  mixtures  which  were 
included  in  this  study.  Some  of  these  are  tabulated  in  condensed 
form  in  Tables  V,  VII  and  IX.  Perhaps  the  most  striking  thing 
brought  out  by  this  series  of  experiments  is  the  fact  that  in  cer- 
tain cases  animal  tissues  are  more  effective  for  enhancing  the 
value  of  cereal  proteins  than  are  the  proteins  of  milk.  Thus  a 
mixture  of  rolled  oats  supplying  6  per  cent  and  milk  supplying 
3  per  cent  of  protein  was  found  to  be  inferior  to  a  similar  com- 
bination of  oats  and  liver,  but  about  equal  in  value  to  mixtures 
of  oat  proteins  and  beef  muscle  or  beef  kidney,  where  the  cereal 


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116     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

furnished  two-thirds  of  the  total  protein  and  the  animal  tissue 
the  remainder.  Barley  and  milk  proteins  likewise  proved  in- 
ferior to  barley  and  animal  tissue  proteins.  Wheat  and  milk, 
while  very  good  as  a  source  of  proteins  when  combined  in  the 
proportions  adhered  to  in  these  experiments,  was  inferior  to 
combinations  of  wheat  and  animal  tissues.  Soy  bean  or  pea 
proteins  appeared  to  be  about  as  well  enhanced  by  milk  proteins 
as  by  the  three  animal  tissues  studied. 

117.  The  Problem  of  Estimating  the  Value  of  Any  Diet  Is 
a   Complicated   One. — These    observations,   together   with   the 
data  presented  in  another  chapter  showing  the  profound  damage 
resulting  from  lack  of  sufficient  of  the  essential  mineral  elements 
or  of  the  three  well  established  vitamins,  illustrate  how  compli- 
cated is  the  problem  of  interpreting  quality  in  a  diet.     One  can 
never  safely  focus  the  attention  upon  a  single  factor  and  use 
this  as  a  criterion  of  much  significance.    A  great  deal  of  detailed 
knowledge,  both  of  the  chemistry  of  food-stuffs  and  also  of  the 
nutritive  needs  of  the  body,  is  essential  to  the  formation  of  safe 
judgments  regarding  any  problem  in  nutrition. 

Holding  in  mind  the  data  presented  in  this  chapter,  one  is 
naturally  inclined  to  turn  one's  thoughts  to  the  studies  in  experi- 
mental nutrition  which  have  been  conducted  upon  human  sub- 
jects, and  to  evaluate  them  anew  in  the  light  of  newer  observa- 
tions on  animals.  Conspicuous  among  nutrition  studies  on  man 
are  those  of  Chittenden  (11)  and  of  Benedict  (12).  Since  far- 
reaching  deductions  have  been  drawn  from  these  results  a  few 
words  of  comment  are  called  for  in  reference  to  their  trustworthi- 
ness as  a  basis  of  guidance  in  deciding  upon  a  safe  dietary 
regimen  for  man. 

1 1 8.  Chittenden's    Experiments    with    Low    Protein    Di- 
etaries.— Chittenden    conceived   the    idea   that    a    low    protein 
dietary,  when  it  is  derived  from  a  suitable  variety  of  wholesome 
foods,  will  best  meet  the  nutritive  requirements  of  the  body.    He 
emphasized  the  logic  of  relieving  the  organs  of  the  task  of  de- 
grading daily  more  protein  than  is  necessary  for  the  repair  of 
tissue  waste.    He  also  emphasized  the  fact  that  the  body  does 
not  tend  to  store  protein  which  is  ingested  in  excess  of  the  daily 
need,  and  that  an  excessive  protein  ingestion  promotes  putrefac- 
tive decomposition  in  the  intestine,  and  results  in  the  absorption 
of  products  which  are  physiological  abominations.    The  logical 
deduction  from  this  reasoning  was  that  the  protein  intake  should 


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119 


120     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

be  reduced  to  as  low  a  level  as  will  serve  to  keep  the  body  in 
nitrogen  or  protein  equilibrium. 

In  order  to  demonstrate  whether  such  a  regimen  is  safe  for 
the  adult  Chittenden  tested  upon  himself  the  proposition  which 
had  hitherto  been  accepted  on  the  authority  of  Voit  and  of  At- 
water,  that  the  average  adult  at  medium  work  requires  about 
116-120  grams  of  protein  per  day.  He  was  able  to  reduce  his 
protein  intake  to  about  one-third  this  amount  and  as  a  result 
felt  better  and  was  clearer  mentally  than  he  had  been  on  a  more 
liberal  protein  dietary.  A  brief  comment  has  already  been  given 
of  the  experimental  demonstration  which  he  planned  and  car- 
ried out  during  1903-04  at  Yale  University,  in  which  a  group 
of  faculty  men,  a  group  of  students  and  a  group  of  soldiers  par- 
ticipated. During  a  period  of  nine  months  while  this  study  was 
going  on  the  men  reduced  their  protein  intake  to  about  half  the 
accepted  standard  requirements.  There  was  no  evidence  that 
these  men  were  not  in  excellent  physical  condition  at  the  end  of 
the  period  of  observation,  and  the  deduction  was  drawn  that 
such  a  dietary  regimen  appeared  for  an  indefinite  period  to  be 
suitable  for  the  maintenance  of  physiological  well-being  in  the 
adult. 

Reference  has  also  been  made  to  the  experiments  of  F.  G. 
Benedict,  which  covered  the  period  of  a  school  year,  the  experi- 
mental subjects  being  a  college  group  of  volunteer  students. 
This  investigator  was  led  to  abandon  his  earlier  view  that  a 
liberal  protein  dietary  best  serves  the  promotion  of  physical 
health,  and  to  conclude  that  his  experience  with  young  men  re- 
stricted for  a  few  months  to  an  abstemious  diet  low  in  protein 
warranted  the  acceptance  of  the  dietary  principles  enunciated 
by  Chittenden. 

119.  Animal  Experiments  Indicate  That  Liberal  Protein 
Intake  Best  Promotes  Health, — The  systematic  and  very 
extensive  nutrition  studies  on  animals  during  recent  years, 
seem  to  place  in  a  new  light  the  older  literature  relating  to 
human  nutrition.  There  is  no  instance  in  our  experience  where 
a  diet  satisfactory  in  all  other  respects,  but  supplying  just  suffi- 
cient protein  of  good  quality  to  support  growth  at  approximately 
the  maximum  rate  to  the  full  adult  size,  has  been  found  to  pro- 
mote as  satisfactory  nutrition  over  the  entire  span  of  adult  life 
as  would  the  same  diet  containing  a  more  liberal  supply  of  the 
protein  factor.  It  has  been  frequently  assumed  by  students  and 
teachers  of  nutrition  that  after  growth  has  been  attained  the 


PECULIARITIES  OF  COMPOSITION  OF  PROTEINS    121 

nutritive  needs  of  the  body  for  protein  food  can  safely  be  met  by 
a  dietary  regimen  in  which  the  protein  content  is  lower  than  is 
essential  for  optimal  growth.  Of  the  numerous  experimental 
data  from  the  work  of  McCollum  and  Simmonds,  none  support 
this  view.  Rather  do  they  all  point  to  the  conclusion  that  when 
the  life  history  of  the  individual  is  considered,  a  generous  pro- 
tein ingestion  or  one  allowing  a  fair  margin  of  safety  over  the 
lowest  percentage  which  just  suffices  to  induce  maximal  growth 
in  the  young  will  serve  to  maintain  optimal  vigor  for  the  longest 
possible  period. 

BIBLIOGRAPHY 

1.  Johns,  C.  0.,  and  Waterman,  H.  C.:     Some  proteins  from  the  Georgia 

velvet  bean,  Jour.  Biol.  Chem.,  1920,  xlii,  59. 

Johns,    C.   O.,   and   Chernoff,   L.    H.:      The    globulin    of   buckwheat, 
Fagopyrum,  Ibid.,  1918,  xxxiv,  439. 

2.  Osborne,  T.  B.,  and  Mendel,  L.  B.:     The  relative  values  of  certain 

proteins  and  protein  concentrates  as  supplements  to  corn  gluten, 
Jour.  Biol.  Chem.,  1917,  xxxi,  69. 

3.  Osborne,  T.  B.,  Mendel,  L.  B.,  and  Ferry,  E.  L.:    A  method  of  express- 

ing numerically  the  growth-promoting  value  of  proteins,  Jour.  Biol. 
Chem.,  1919,  xxxvii,  223. 

4.  Osborne,  and  Mendel:     The  role  of  vitamines  in  the  diet,  Jour.  Biol. 

Chem.,  1917,  xxxi,  149. 

5.  McCollum,  E.  V.,  Simmonds,  Nina,  and  Parsons,  H.  T.:     Supplemen- 

tary relationships  between  the  proteins  of  certain  seeds,  Jour.  Biol. 
Chem.,  1919,  xxxvii,  155. 

6.  Hart,  E.  B.,  McCollum,  E.  V.,  and  Fuller,  J.  G.:    The  role  of  inorganic 

phosphorus  in  the  nutrition  of  animals,  Wis.  Exp.  Sta.  Res.  Bull. 

No.  1 ;  Amer.  Jour,  of  Physiol.,  1909,  xxiii,  246. 
McCollum,  E.  V.:    Notes  on  the  creatinine  excretion  of  the  pig,  Amer. 

Jour,  of  Physiol.,  1911,  xxix,  210. 
McCollum:     Nature  of  the  repair  processes  of  protein  metabolism, 

Wisconsin  Agr.  Exp.  Sta.  Res.  Bull.,  No.  21,  1912. 
McCollum,  E.  V.,  and  Steenbock,  H. :     On  the  creatinine  metabolism  of 

the  growing  pig,  Jour.  Biol.  Chem.,  1912,  xiii,  209. 
McCollum,  E.  V.,  and  Hoagland,  D.  R.:     Studies  of  the  endogenous 

metabolism  of  the  pig  as  modified  by  various  factors:     1.  The  effect 

of  acid  and  of  basic  salts,  and  of  free  mineral  acids  on  the  endogenous 

nitrogen  metabolism,  Jour.  Biol.  Chem.,  1913,  xvi,  299. 

2.  The   influence   of  fat   feeding   on   endogenous  nitrogen   meta- 

bolism, Ibid.,  317. 

3.  The    influence    of   benzoic   acid    on   the    endogenous    nitrogen 

metabolism,  Ibid.,  321. 

7.  McCollum,  Simmonds,  and  Parsons:     Supplementary  protein  values  in 

foods. 

1.  The  nutritive  properties  of  animal  tissues,  Jour.  Biol.  Chem., 

1921,  xlvii,  111. 

2.  Supplementary   dietary   relations   between   animal   tissues   and 

cereal  and  legume  seeds,  Ibid.,  139. 


122     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

3.  The  supplementary   dietary  relation  between  the  proteins  of 

cereal  grains  and  potato,  Ibid.,  175. 

4.  The  supplementary  relations  of  cereal  grain  with  cereal  grain; 

legume  seed  with  legume  seed;  and  cereal  grain  with  legume 
seed,  with  respect  to  improvement  in  the  quality  of  their 
proteins,  Ibid.,  207. 

5.  Supplementary  relations  of  the  proteins  of  milk  for  those  of 

cereals,  and  of  milk  for  those  of  legume  seeds,  Ibid.,  235. 

8.  Osborne,  and  Mendel.:     Amino-acids  in  nutrition  and  growth,  Jour. 

Biol.  Chem.,  1914,  xvii,  325. 

Nutritive  properties  of  the  maize  kernel,  Ibid.,  1914,  xviii,  1. 
The  comparative  nutritive  value  of  certain  proteins  in  growth  and 
the  problem  of  the  protein  minimum,  Ibid.,  1915,  xx,  351. 

9.  Rubner,  M.:     Die  Gesetze  des  Energieverbrauchs  bei  der  Ernahrung, 

1902,  Leipsig  und  Wien. 

10.  Osborne,   and    Mendel:      Nutritive   factors   in   plant   tissues.     1.  The 

protein    factor   in   the   seeds    of   cereals,   Jour.    Biol.    Chem.,    1918, 
xxxiv,  521. 

11.  Chittenden,  R.  H.:     Physiological  economy  in  nutrition,  New  York, 

1904. 
The  nutrition  of  man,  New  York,  1907. 

12.  Benedict,  F.  G.:     The  nutritive  requirements  of  the  body,  Amer.  Jour. 

of  Physiol.,  1906,  xvi,  409. 

Physiological    effects    of   a    prolonged   reduction   in   the    diet    on 

twenty-five  men,  Trans.  Amer.  Philosophical  Soc.,  1918,  Ivii,  479. 

Benedict,  F.  G.,  and  Roth,  P.:     The  metabolism   of  vegetarians  as 

compared  with  the  metabolism  of  non-vegetarians  of  like   weight 

and  height,  Jour.  Biol.  Chem.,  1915,  xx,  231. 
Benedict,  F.  G.,  and  Smith,  H.  M.:     The  metabolism  of  athletes  as 

compared   with  normal   individuals   of  similar  height  and   weight, 

Ibid.,  243. 
Benedict,   F.   G.,   and   Emmes,   L.   E.:     A   comparison   of   the   basal 

metabolism  of  normal  men  and  women,  Ibid.,  253. 
Benedict:    Factors  effecting  basal  metabolism,  Ibid.,  263. 


FIG.  7. — The  rations  of  these  two  rats  had  the  same  composition  as  shown  by  chemical 
analysis.  They  differed  only  in  the  source  of  the  protein  which  they  contained.  The  rat 
on  the  right  grew  up  on  a  mixture  of  proteins  from  the  corn  kernel  and  wheat  gluten  ;  that 
on  the  left  on  a  mixture  of  corn  proteins  and  gelatin.  The  difference  in  size,  and  remark- 
able difference  in  appearance  is  solely  the  result  of  the  difference  in  the  quality  of  the 
proteins  in  the  two  diets.  Corn  proteins  and  gelatin  do  not  supplement  each  other's  amino- 
acid  deficiencies.  These  animals  were  the  same  age  when  photographed,  and  had  been  con- 
fined for  the  same  number  of  days  to  the  experimental  diets. 


CHAPTER  VI 

THE  DIETARY  PROPERTIES  OF  INDIVIDUAL 
FOOD-STUFFS 

120.  Results  Obtained  with  the  Biological  Method  for  the 
Analysis  of  a  Food-stuff. — In  preceding  chapters  an  effort  has 
been  made  to  give  what  we  actually  know  about  what  constitutes 
in  chemical  terms  a  satisfactory  diet,  and  the  type  of  experi- 
mental procedure  by  means  of  which  this  knowledge  was  gained. 
For  the  purpose  of  placing  this  knowledge  in  proper  perspective 
and  correlating  it  with  the  older  views  of  problems  in  nutrition 
a  brief  account  of  certain  earlier  investigations  and  the  deduc- 
tions made  therefrom  were  presented.  With  the  object  of  broad- 
ening the  vision  of  the  present  day  investigators  so  as  to  enable 
them  and  their  successors  in  this  field  to  appreciate  how  care- 
fully experimental  work  must  be  planned  and  controlled  in  order 
to  avoid  conclusions  which  tend  to  confuse  rather  than  clarify, 
a  critical  examination  of  the  technic  of  experimental  methods 
has  been  included. 

It  will  be  appreciated  how  confusing  was  the  task  of  interpret- 
ing the  cause  of  failure  or  success  with  experimental  diets,  when 
it  is  recalled  that  a  few  years  ago  no  definite  conception  was 
possible  of  the  existence  of  at  least  three  dietary  factors  which 
are  indispensable  in  the  food  supply  of  man  or  certain  animals. 
Fortunately  for  students  in  this  field  the  rat  requires  but  two  of 
these,  and  this  species  therefore  assumes  special  value,  in  gaining 
a  satisfactory  working  hypothesis  regarding  the  number  of  es- 
sential factors  in  its  nutrition.  Even  with  this  species,  however, 
in  addition  to  the  two  unknown  factors  there  were  two  variables, 
either  of  which  might  determine  success  or  failure  in  the  devel- 
opment of  this  species.  These  were  the  quality  of  the  proteins, 
and  the  amounts  of  certain  mineral  elements  contained  in  the 
food  mixture.  The  solution  of  such  a  problem  demanded  first  the 
accumulation  of  a  considerable  amount  of  data  based  upon  the 
outcome  of  a  series  of  experiments,  each  of  which  was  not  pos- 
sible of  interpretation  except  in  the  light  of  all  the  others.  It 
must  be  admitted  that  success  was  actually  in  no  small  measure 

123 


124     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

the  result  of  active  imagination  and  successful  theorizing  as  to 
the  true  meaning  of  the  effects  of  the  experimental  diets  on  the 
animals  observed. 

In  order  to  understand  how  foods  should  be  combined  so  as 
to  make  good  each  other's  deficiencies,  it  is  necessary  to  describe 
the  dietary  properties  of  each  of  the  more  important  natural 
foods.  This  will  form  the  subject  of  the  present  chapter. 

121.  Wheat. — This  is  the  most  important  seed  grain  used  as 
food  by  all  western  peoples,  and  is  second  only  to  rice  in  respect 
to  the  quantity  used  as  food  for  man.  The  latter  is  in  greatest 
favor  among  peoples  of  the  eastern  hemisphere.  The  dietary 
properties  of  the  wheat  kernel  have  been  described  in  Chapter  II 
in  connection  with  the  development  of  the  biological  method  for 
the  analysis  of  a  food-stuff.  The  proteins  of  this  grain  are  about 
as  efficient  for  the  promotion  of  growth  as  are  the  same  amounts 
of  protein  from  milk  or  eggs,  or  of  certain  combinations  of  two 
or  more  foods  whose  proteins  are  so  constituted  as  to  supplement 
each  other's  deficiencies.  There  is  no  cereal  grain  yet  adequately 
studied  which  has  been  found  to  contain  proteins  superior  to 
those  of  wheat.  Its  prominent  place  in  the  diet  of  mankind  is, 
therefore,  justified  by  the  results  of  experiments  on  animals. 
When  the  wheat  kernel  is  satisfactorily  supplemented  with  re- 
spect to  all  other  dietary  factors,  its  proteins  have  proven  satis- 
factory for  the  promotion  of  ordinary  growth  and  the  mainte- 
nance of  good  nutrition  over  a  considerable  fraction  of  the  normal 
span  of  life  of  the  rat,  even  when  the  protein  content  of  the  food 
mixture  did  not  exceed  9  per  cent  of  its  calorific  value.  This  is 
illustrated  by  the  records  in  Chart  4.  The  results  of  feeding 
diets  in  which  wheat  was  the  sole  source  of  protein  have  not  been 
uniformly  successful,  and  it  appears  that  some  samples  of  wheat 
are  superior  to  others.  It  is  well  known  that  the  quality  of  the 
proteins  vary  markedly  in  different  samples  of  wheat,  with  re- 
spect to  their  glutinous  property  so  important  in  bread-making, 
and  the  reason  for  this  seems  not  to  have  been  satisfactorily  ex- 
plained. It  may  be  due  in  part  at  least  to  variability  in  the  pro- 
portions among  the  several  individual  proteins  in  the  seed.  If 
this  is  true,  it  would  account  for  such  inequalities  in  nutritional 
value  as  have  been  observed. 

Wheat  is  too  poor  in  calcium  to  meet  the  needs  of  the  grow- 
ing rat.  The  average  content  of  this  element  per  100  grams  of 
this  cereal  is  about  0.041  gram.  The  optimum  content  of  cal- 
cium for  the  growing  rat  is  not  far  from  0.64  per  cent  of  the 


DIETARY  PROPERTIES  OF  FOODSTUFFS        125 

food  mixture.  Phosphorus,  sodium,  chlorin  and  iodin  are  also 
present  in  the  wheat  kernel  in  amounts  too  low  to  support  normal 
nutrition  in  this  species.  The  content  of  mineral  elements  in  any 
plant  product  is  subject  to  some  variation,  depending  upon  sev- 
eral factors,  chief  among  which  is  the  content  of  each  of  the 
several  inorganic  ions  in  the  soil.  The  amount  of  water  tran- 
spired during  the  growth  of  the  plant  is  also  a  controlling 
factor  (1). 

In  general  the  entire  wheat  kernel  is  not  used  as  human  food, 
and  the  grain  is  fed  to  animals  only  under  exceptional  circum- 
stances, because  it  is  usually  more  valuable  for  the  manufacture 
of  flour.  Bread  made  from  whole  wheat  is  dark  in  color,  but  has 
a  flavor  which  is  very  agreeable.  Whole  wheat  flour  does  not 
possess  very  good  keeping  qualities.  The  germ  of  the  seed 
(wheat  embryo)  is  rich  in  oil,  and  this  tends  to  become  rancid 
when  the  kernel  is  broken  by  milling.  The  rancidity  spoils  the 
flavor  of  the  flour.  Furthermore,  the  insects  which  infest  cereals 
select  the  germ  as  the  site  for  the  deposition  of  their  eggs,  so  that 
whole  wheat  flour  contains  many  more  insect  eggs  than  does  flour 
free  from  germ. 

122.  Wheat  Germ. — This  constitutes  but  1.5  per  cent  of  the 
entire  kernel.  It  contains  more  than  35  per  cent  of  protein. 
Bran  forms  about  15  per  cent  of  the  kernel  and  contains  17-19 
per  cent  of  protein.  The  remainder  of  the  seed,  about  83  per 
cent,  is  endosperm,  containing  about  11  per  cent  of  protein. 

Wheat  germ  has  dietary  properties  exceptionally  valuable  in 
several  respects  (2).  Its  proteins  are  abundant  and  are  of  good 
quality;  its  content  of  the  essential  mineral  elements  is  much 
greater  than  in  bolted  flour;  it  is  exceptionally  rich  in  the  anti- 
neuritic  substance,  water-soluble  B,  and  contains  a  considerable 
amount  of  fat-soluble  A.  Probably  enough  of  the  latter  sub- 
stance is  present  to  meet  the  needs  of  the  growing  rat  if  germ 
constituted  about  75  per  cent  of  the  diet.  Strange  to  say,  it  con- 
tains but  very  little  of  the  anti-scorbutic  substance,  water-soluble 
C  (3).  The  oil,  of  which  the  germ  contains  about  10  per  cent, 
leaves  a  somewhat  unpleasant  after  taste,  and  is  somewhat  in- 
jurious to  animals  (4). 

The  germ  contains  a  yellow  pigment  in  considerable  amount 
and  this  contributes  to  the  color  of  whole  wheat  flour.  The  color 
of  the  latter  is,  however,  due  principally  to  the  bran  layer.  In 
order  to  make  flour  white,  it  is  necessary  to  remove  both  the  germ 
and  the  bran.  The  germ  is  plastic  and  can  be  removed  in  the 


126     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

form  of  a  large  flake  if  the  kernel  is  broken  by  a  series  of  blows 
instead  of  by  the  old  time  grinding  process  for  making  flour. 
This  is  accomplished  in  modern  milling  by  the  roller  process  in 
which  the  kernels  are  broken  by  passing  between  rollers  so  set 
as  to  crush  them.  This  method  for  reducing  the  wheat  grain  to 
a  powder  leaves  the  bran  in  large  flakes  which  can  be  separated 
from  the  fine  flour  and  the  germ  by  mechanical  processes.  The 
part  which  goes  to  make  bolted  flour  is  that  which  is  readily 
crushed  by  the  rollers  to  a  fine  powder.  It  is  separated  from  the 
low  grade  flour  by  passing  through  bolting  cloth.  The  low  grade 
flour,  so-called,  is  made  up  to  a  great  extent  of  the  same  parts 
of  the  kernel  as  the  high  grade  or  white  flour,  but  contains  in 
addition  numerous  very  small  flakes  of  bran  with  particles  of 
flour  attached  thereto. 

For  some  reason  or  other  wheat  germ  as  a  stock  feed  has  never 
found  favor  with  farmers,  and  in  recent  times  no  effort  has  been 
made  to  market  the  pure  product  for  feeding  purposes.  It  is 
mixed  with  bran  or  a  low  grade  flour  known  as  middlings,  and 
reaches  the  feeder  in  this  mixed  form.  This  is  apparently  the 
best  use  to  make  of  it.  Through  private  correspondence  the 
author  has  been  informed  that  a  few  persons,  in  districts  not 
far  removed  from  the  milling  centers,  have  employed  wheat  germ 
as  a  breakfast  cereal.  Its  tendency  to  rancidity  and  to  become 
infested  with  insects  would  prohibit  its  being  marketed  in  the 
same  manner  as  breakfast  cereals  in  general.  For  the  same  rea- 
son it  appears  that  the  logical  use  of  this  product  is  the  one  now 
in  vogue,  since  the  great  centers  of  the  milling  industry  are  near 
the  great  stock-producing  areas. 

123.  Bolted  Wheat  Flour. — In  point  of  quantity  consumed, 
white  flour  is  the  most  important  article  of  diet  of  the  American 
people,  and  is  widely  used  in  Europe.  This  is  remarkable  be- 
cause it  is  notably  deficient  in  more  dietary  factors  than  any 
other  single  food  which  enters  in  a  large  way  into  the  diet  of 
man,  except  sugars,  starches  and  fats  which  are  marketed  in  the 
pure  state.  Muscle  meats  are,  however,  almost  in  the  same  class. 
Bolted  flour  consists  essentially  of  starch,  proteins  and  inorganic 
salts.  Its  proteins  are  of  relatively  poor  quality,  and  its  mineral 
components  are  conspicuously  lacking  in  calcium,  sodium,  chlorin, 
iron  and  phosphorus,  some  of  the  essential  elements  we  regu- 
larly expect  to  find  in  satisfactory  abundance  in  our  foods  (5) . 

The  proteins  of  bolted  flour  are  practically  limited  to  two. 
These  are  called  gliadin  and  glutenin,  both  of  which  are  very 


DIETARY  PROPERTIES  OF  FOODSTUFFS        127 

unlike  any  of  the  proteins  in  the  animal  body  from  the  stand- 
point of  their  yield  of  the  different  amino-acids.  These  proteins 
are  not  constituted  so  as  to  enhance  each  other's  value  as  food 
by  compensating  each  other's  deficiencies,  and  cannot,  therefore, 
be  effectively  transformed  into  body  proteins  unless  they  are 
combined  with  other  foods  wisely  chosen  (6).  Wheat  flour  is 
very  deficient  in  all  three  of  the  recognized  unidentified  dietary 
essentials,  fat-soluble  A,  water-soluble  B  and  water-soluble  C, 
the  anti-ophthalmic,  anti-neuritic  and  anti-scorbutic  substances, 
respectively  (7). 

The  merits  of  flour  as  a  food  rest  essentially  upon  the  peculiar 
glutinous  properties  of  its  proteins,  which  make  possible  the 
formation  of  dough.  This  is  sufficiently  tenacious  to  permit  of 
leavening  by  the  generation  of  carbon  dioxid  gas  within  it, 
through  the  agency  of  yeast  or  baking  powder.  By  this  means 
light  spongy  bread  is  secured,  which  has  a  pleasant  flavor,  and 
a  texture  which  invites  mastication.  Bread  and  meat  are  the 
only  foods  which  are  prominent  in  the  American  diet  which  are 
chewed  to  any  appreciable  extent.  Of  these,  bread  is  by  far  the 
most  important  in  this  respect.  Bolted  flour  possesses  still  an- 
other virtue.  It  has  excellent  keeping  qualities  and  can  be  dis- 
tributed without  commercial  hazard  over  wide  areas  from  the 
milling  centers.  This  is  a  matter  of  great  importance  in  a  coun- 
try like  the  United  States.  It  will,  despite  its  shortcomings  from 
a  dietary  standpoint,  remain  our  most  important  energy-yielding 
food. 

It  is  not  to  be  understood  from  what  has  been  said  that  wheat 
flour  is  not  a  wholesome  food.  When  properly  combined  with 
such  other  foods  as  make  a  well  proportioned  diet,  every  factor 
of  which  is  so  adjusted  as  to  meet  the  needs  of  the  body,  it  be- 
comes an  entirely  satisfactory  part  of  the  diet.  The  keynote  to 
the  discussion  of  the  individual  foods  entering  into  the  diet  of 
man  is  the  importance  of  using  proper  combinations  of  foods. 

124.  Bolted  Wheat  Flour  Need  Not  Be  Condemned  Be- 
cause of  Its  Deficiencies. — The  attitude  which  one  should  take 
toward  the  discussion  of  the  relative  merits  of  bolted  as  against 
whole  wheat  flour  is  now  easy  to  understand  and  appreciate. 
The  latter  is  decidedly  more  suitably  constituted  to  maintain 
well-being  for  a  short  time  if  it  serves  as  the  sole  article  of  diet, 
as  it  might  under  conditions  approaching  famine.  Whole  wheat 
flour  is,  however,  a  decidedly  incomplete  food,  and  needs  to  be 
supplemented  with  other  foods  in  order  to  compensate  for  its 


128     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

deficiencies.  The  unfortunate  individual  who  through  faulty 
habits  of  living,  finds  at  an  age  at  which  he  should  be  still  in 
possession  of  the  full  vigor  of  middle  life,  that  his  efficiency  is 
diminishing  and  the  joy  of  living  slipping  away,  has  not  infre- 
quently turned  for  relief,  to  substituting  whole  wheat  flour  for 
the  staple  white  variety.  As  a  rule  those  who  advocate  this 
practice  exhibit  in  some  degree  the  spectral  mien  of  the  dyspeptic. 
They  would  gain  much  more  through  adhering  to  a  diet  well 
balanced  than  through  clutching  to  this  or  any  other  dietary 
whim  or  fad. 

Wheat  bran  has  been  studied  by  Osborne  and  Mendel  (5). 
Their  results  indicate  that  the  proteins  of  this  part  of  the  kernel 
have  a  higher  value  than  those  of  the  germ,  and  that  they  are 
distinctly  superior  to  those  of  bolted  flour.  Their  findings  were 
not  concordant,  since  but  one  rat  in  four  succeeded  in  growing 
on  their  experimental  diet.  Bran  is  much  poorer  in  water-soluble 
B  than  is  the  germ.  They  found  5  per  cent  of  bran  as  the  sole 
source  of  this  factor  to  be  entirely  inadequate.  McCollum,  Sim- 
monds  and  Pitz,  have  observed  normal  growth  in  young  rats 
during  five  months  with  diets  in  which  this  substance  was  en- 
tirely derived  from  2  per  cent  of  germ,  and  Osborne  and  Mendel 
have  also  found  5  per  cent  of  the  latter  to  furnish  sufficient 
water-soluble  B  (2). 

No  studies  by  means  of  biological  methods  have  been  made  of 
the  adequacy  of  the  mineral  content  of  bran,  but  one  may  judge 
fairly  safely  from  the  results  of  chemical  analysis  that  it  is  too 
poor  in  calcium  and  probably  also  in  sodium  and  chlorin.  It 
contains  but  little  of  the  factor,  fat-soluble  A.  This  statement 
is  not  made  upon  the  results  of  a  direct  test,  but  on  inference 
from  the  well-known  fact  that  the  entire  wheat  kernel  is,  like 
most  seeds,  well  below  the  optimum  in  its  content  of  this  sub- 
stance, for  the  amount  contained  in  the  kernel  is  in  great  measure 
located  in  the  germ.  Bran  constitutes  about  15  per  cent  of  the 
entire  kernel,  and  could  not  be  expected  to  contain  much  of  it. 

125.  Maize  Kernel. — This  cereal  grain  has  dietary  properties 
very  similar  to  those  of  wheat.  Its  flavor  and  physical  properties, 
however,,  are  very  different.  Since  its  proteins  have  none  of  the 
glutinous  properties  it  is  not  possible  to  form  a  dough  with  finely 
ground  maize.  In  the  Southern  United  States  maize  is  much 
prized  as  a  human  food.  It  was  found  in  a  dietary  study  to 
constitute  23  per  cent  of  the  total  food  intake  of  Tennessee  and 
Georgia  mountaineers,  and  32.5  per  cent  of  that  of  Southern 


DIETARY  PROPERTIES  OF  FOODSTUFFS        129 

negroes.  Among  72  Northern  families  in  comfortable  circum- 
stances only  1.6  per  cent  of  the  diet  was  derived  from  this 
grain  (8) .  The  great  bulk  of  the  maize  crop,  which  in  this  coun- 
try amounted  to  three  billion  bushels  in  1917,  is  used  in  stock 
feeding. 

The  proteins  of  maize  have  a  slightly  lower  value  in  nutrition 
when  fed  as  the  sole  source  of  this  dietary  factor,  than  have  those 
of  wheat.  Its  mineral  deficiencies  are  the  same  as  those  of  the 
latter.  These  two  grains  are  about  comparable  in  their  content 
of  anti-neuritic  substance,  water-soluble  B.  It  requires  about 
15  per  cent  of  the  food  mixture  of  either,  when  they  serve  as  the 
sole  source  of  this  factor,  to  enable  young  rats  to  grow  in  a  nor- 
mal manner.  With  such  a  diet,  however,  a  female  rat  cannot 
successfully  nourish  four  young  during  the  nursing  period,  even 
when  all  other  factors  are  highly  satisfactory.  For  this  purpose 
about  half  of  the  diet  must  be  derived  from  a  cereal  grain,  pro- 
vided there  is  no  other  source  of  the  anti-neuritic  substance. 
Neither  grain  contains  an  appreciable  amount  of  the  anti-scor- 
butic substance,  water-soluble  C,  unless  it  is  germinated.  Dur- 
ing this  process  there  is  a  rapid  increase  in  their  potency  as  foods 
protective  against  scurvy  (9) . 

126.  Vitamin  Content  of  Different  Samples  of  the  Same 
Food  Varies  Considerably. — Much  effort  has  been  expended  in 
recent  years  by  a  number  of  investigators,  with  a  view  to  de- 
termining very  accurately  the  vitamin  content  of  different  foods. 
It  has  seemed  to  McCollum  and  Simmonds,  from  the  results  of 
their  studies,  that  this  matter  has  excited  greater  interest  than 
its  importance  justifies.  They  found  in  numerous  comparative 
studies  that  different  samples  of  cereal  grains  differ  considerably 
in  their  content  of  water-soluble  B.  Steenbock's  observations 
relative  to  the  differences  in  fat-soluble  A  content  of  different 
samples  of  maize,  is  another  evidence  which  supports  the  view 
that  rather  general  statements  as  to  the  relative  values  of  many 
of  our  common  foods  with  respect  to  the  uncharacterized  dietary 
essentials  is  all  that  we  can  profitably  seek  to  make  on  the  basis 
of  experimental  tests.  We  are  already  in  possession  of  about  all 
the  specific  information  in  this  field  that  we  can  make  practical 
use  of.  The  fact,  that  we  can  readily  prepare  diets  from  ordi- 
nary wholesome  foods  which  will  contain  at  least  three  to  five 
times  the  minimum  amounts  of  vitamins  on  which  apparently 
normal  nutrition  can  be  maintained  over  long  periods,  tends  to 
render  the  discussions,  which  one  so  frequently  sees  nowadays 


130      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

about  the  advisability  of  taking  concentrated  commercial  prep- 
arations of  vitamins,  a  purely  academic  one,  and  based  upon 
fallacious  reasoning  and  lack  of  clarity  of  vision  or  of  familiarity 
with  existing  literature  describing  experimental  data. 

127.  Fat-Soluble  A  Content  of  Yellow  and  Other  Varieties 
of  Maize.— Steenbock  and  Boutwell  (10)   observed  that  yellow 
maize  is  far  superior  to  white  or  red  varieties  as  a  source  of  fat- 
soluble  A.    They  believed  at  one  time  that  the  fat-soluble  A  is 
in  general  associated  with  the  yellow  pigment  of  plants.    This 
view  has  been  in  great  measure  discarded. 

Maize  which  is  used  as  human  food  is  now  freed  from  its  germ 
and  its  bran  layer  in  a  manner  analogous  to  wheat,  and  also  for 
the  purpose  of  improving  its  appearance  and  more  especially  its 
keeping  qualities.  Maize  germ,  like  wheat  germ,  is  rich  in  oil  and 
this  tends  to  become  rancid  when  the  kernel  is  ground  and  ex- 
posed to  the  air.  Meal  which  contains  the  germ  is  more  liable 
to  harbor  insects  when  kept  over  a  period  of  warm  weather,  than 
is  ordinary  corn  meal.  Both  white  and  yellow  grain  is  used  for 
making  meal  for  human  consumption.  The  former  is  in  greatest 
general  favor  with  the  public  because  it  has  been  educated  to  a 
liking  for  white  flour  and  white  rice.  Corn  oil  is  now  marketed 
as  a  salad  oil. 

128.  Oats. — Rolled  oats  are  used  in  America  in  human  nutri- 
tion principally  as  a  breakfast  food.     Oats  have  long  been  a 
principal  food  grain  in  Scotland.    The  oat  kernel  is  comparable 
with  wheat  or  maize  in  its  dietary  properties  in  nearly  all  re- 
spects.   It  appears  from  the  data  available  that  there  is  distinctly 
less  fat-soluble  A  in  rolled  oats  than  in  wheat  and  certainly 
much   less  than  in  yellow  maize.     There   is  no   demonstrable 
amount  of  anti-scorbutic  substance  in  the  oat  kernel. 

Oats  have  been  a  great  favorite  among  feeders  of  horses,  and 
are  believed  by  many  to  have  exceptionally  high  nutritive  value 
because  animals  fed  liberally  with  oats  frequently  show  much 
spirit  when  driven  or  ridden.  In  the  experience  of  McCollum 
and  Simmonds,  rats  which  are  fed  on  restricted  diets  of  certain 
types,  faulty  in  one  or  more  respects,  become  restless,  irritable 
and  apprehensive,  and  the  thought  occurs  that  perhaps  the  com- 
mon expression  among  horsemen  that  an  animal  "feels  his  oats" 
may  have  been  misinterpreted.  The  tendency  of  horses  fed  lib- 
erally on  this  grain  to  exert  themselves  greatly  without  urging 
may  be  the  result  of  increased  irritability  and  apprehensiveness. 

129.  Rice. — This  is  the  most  important  cereal  grain  in  the 
diet  of  more  than  half  of  the  human  race,  especially  that  portion 


DIETARY  PROPERTIES  OF  FOODSTUFFS         131 

of  the  race  in  Asia  and  the  islands  of  the  Pacific,  and  is  used  to 
a  considerable  extent  throughout  the  world.  It  has  never  found 
much  favor  in  the  United  States,  but  is  used  in  small  amounts. 
Among  primitive  peoples  rice  is  eaten  without  polishing,  in  which 
form  it  is  known  as  red  rice,  but  it  is  ordinarily  so  treated  as  to 
lose  a  large  part  of  its  germ.  This  loss  results  from  the  pounding 
of  the  kernels  in  rude  mortars  in  which  process  the  germ  is 
separated  from  many  of  the  kernels  and  lost  in  subsequent 
handling.  The  bran  layer,  which  is  richer  in  mineral  salts  than 
the  endosperm  of  the  seed,  is  retained  in  this  process. 

Rice  which  is  used  for  export  and  for  sale  in  the  large  cities 
at  some  distance  from  the  place  of  production,  is  polished  by 
stirring  the  kernels.  The  abrasive  action  results  in  wearing  away 
the  bran.  The  germ  is  in  an  exposed  position  and  easily  rubs 
off  in  this  process  and  is,  therefore,  left  with  the  bran.  This  mix- 
ture is  known  as  rice  polishings.  The  germ  of  rice,  like  that  of 
wheat  or  maize,  consists  of  cellular  structures  which  are  the  seat 
of  protoplasmic  activity,  and  is  a  more  complete  food  than  any 
other  part  of  the  kernel.  It  contains  almost  all  the  fats  found  in 
the  grain,  and  is  more  efficient  in  nourishing  insects  as  well  as 
higher  animals  than  is  the  polished  grain.  Unpolished  rice  loses 
its  flavor  owing  to  the  fats  becoming  rancid,  when  kept  for  con- 
siderable periods  in  a  warm  climate,  whereas  the  polished  kernel 
can  be  handled  without  commercial  hazard  because  it  contains 
almost  no  fat  and  does  not  support  the  growth  of  insect  Iarva3. 

The  practice  of  polishing  rice  had  its  origin  in  the  desire  to 
improve  its  keeping  quality,  and  the  incidental  whitening  of  the 
kernels  has  led  to  the  establishment  of  a  demand  for  a  white 
product.  This,  and  the  artificially  established  liking  for  white 
flour  and  white  corn  meal,  is  an  illustration  of  the  failure  of  the 
instinct  of  man  to  serve  as  a  safe  guide  in  the  selection  of  food. 
The  esthetic  sense  is  appealed  to  in  greatest  measure  in  this  case 
by  the  products  of  lowest  biologic  values. 

Attractiveness  of  rice  to  the  eye  is  so  important  a  factor  com- 
mercially that  the  practice  of  artificial  whitening  of  the  polished 
kernels  has  come  into  vogue.  This  is  accomplished  by  coating 
the  kernels  with  talcum  powder,  the  latter  adhering  by  means 
of  a  thin  coating  of  glucose.  The  milky  appearance  of  the  water 
in  which  rice  is  washed,  is  due  to  the  talcum  remaining  for  a 
time  in  suspension.  Rice  which  has  been  polished  but  not  coated 
in  this  way  is  called  brown  rice  as  contrasted  with  the  coated 
or  white  rice. 

Chart  3  shows  that  there  are  four  dietary  factors  in  which 


132     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

polished  rice  is  of  such  poor  quality  as  to  require  improvement 
before  it  becomes  a  complete  food.  Its  proteins  like  those  of 
other  cereal  grains  are  of  low  biological  value,  and  need  to  be 
enhanced  by  the  addition  of  other  proteins  which  are  so  con- 
stituted as  to  have  a  supplementary  relationship  to  rice  pro- 
teins (11).  It  is  entirely  too  poor  in  all  essential  mineral  ele- 
ments to  meet  the  needs  of  a  growing  animal,  and  is  nearly  free 
from  both  fat-soluble  A  and  water-soluble  B.  The  experi- 
mental data  in  Chart  3  was  obtained  with  the  rat  and  does  not 
bring  out  the  fact  that  rice  is  lacking  in  the  anti-scorbutic  sub- 
stance. This  substance  is  not  essential  in  the  diet  of  the  rat  for 
the  reason  that  this  animal  is  able  to  synthesize  the  complex, 
whereas  man,  monkey  and  guinea  pig  must  secure  their  supply 
from  the  food.  This  point  will  be  further  discussed  in  Chapter 
VIII  in  connection  with  the  deficiency  disease  scurvy. 

130.  Barley  and  Rye. — These  and  apparently  other  cereal 
grains  possess  essentially  the  same  dietary  properties  and  short- 
comings as  do  those  already  described.    Experiments  with  ani- 
mals have  shown  that  they  must  be  improved  in  respect  to  the 
same  factors  in  order  to  make  them  complete  foods  (12). 

131.  Peas  and  Beans. — These  are  seeds  belonging  to  a  class 
of  plants  known  as  legumes,  which  are  able  to  utilize  the  nitro- 
gen of  the  air  for  the  purpose  of  synthesizing  proteins  during 
growth.     Other  plants  have  to  secure  their  nitrogen  from  the 
soil  in  the  form  of  nitrates  or  ammonium  compounds.     The 
legume  seeds  are  much  richer  in  protein  than  are  any  of  the 
cereal  grains.    Wheat,  maize,  oat,  and  rice  kernels  contain  about 
11,  10,  15  and  9  per  cent  of  protein,  respectively,  whereas  peas 
and  beans  contain  about  23  per  cent.    For  this  reason  the  latter 
seeds  have  long  been  regarded  as  especially  valuable  from  the 
standpoint  of  protein  content.     Beans  have  been   frequently 
spoken  of  as  the  "poor  man's  meat."    Unfortunately  modern  ex- 
perimental studies  have  not  lent  support  to  this  view.    Their 
proteins  appear  from  the  results  of  chemical  analysis,  to  be  much 
more  adequately  constituted  than  are  those  of  wheat  or  maize, 
but  nutrition  experiments  on  animals  show  clearly  that  there  is 
something  lacking  in  their  molecules  which  limits  the  extent  to 
which  they  can  be  converted  in  the  body  into  tissue  proteins. 
The  nature  of  the  limiting  factor  has  not  been  determined  (13). 

132.  Osborne  and  Mendel's  Studies  on  Legume  Proteins. — 
Osborne  and  Mendel  (14)  were  unable  to  secure  any  growth  with 
pea  and  bean  proteins  when  these  were  carefully  purified  and 


DIETARY  PROPERTIES  OF  FOODSTUFFS          133 

fed  as  the  principal  source  of  nitrogen  in  the  diet,  the  proteins  of 
the  legume  seeds  being  supplemented  only  with  the  nitrogen  of 
"protein-free  milk."  It  has  been  shown  in  McCollum's  labora- 
tory that  the  protein  mixture  contained  in  the  entire  seed  of  the 
pea  or  bean  is  complete  and  can  support  fair  growth  when  they 
serve  as  the  sole  source  of  protein  in  the  diet.  The  other  defi- 
ciencies in  the  seeds  must,  of  course,  be  made  good.  Growth  is 
possible  only  when  the  intake  of  protein  in  such  diets  is  rather 
high  (13).  The  proteins  of  these  seeds  are  distinctly  poorer  in 
quality  than  are  the  combinations  of  proteins  found  in  each  of  the 
cereal  grains.  Beans  contain  considerable  amounts  of  hemicellu- 
loses  which  are  not  digestible  but  easily  fermented  in  the  intes- 
tine with  the  formation  of  gas  and  frequently  cause  flatulence. 

A  matter  of  great  importance  in  comparing  the  relative  values 
of  the  proteins  of  the  legume  seeds  with  those  of  meats,  is  the 
extent  to  which  each  supplies  an  abundance  of  those  particular 
amino-acids  which  are  not  yielded  in  optimal  amounts  by  the 
proteins  of  the  cereal  grains  and  tubers.  The  cereals  form,  in 
temperate  climates,  the  greater  fraction  of  our  foods  and  supply 
most  of  the  protein  and  energy  of  the  diet.  The  milled  products 
of  these  contain  proteins  of  relatively  low  value  and  are 
deficient,  without  exception,  in  certain  amino-acids.  They  may, 
when  combined,  mutually  improve  each  other  to  a  certain 
extent,  but  there  are  some  essential  amino-acids  which  are  not 
abundant  even  in  mixtures  of  several  grains.  In  looking  toward 
improvement  of  a  dietary  consisting  largely  of  milled  cereal 
products  one  of  the  important  factors  is  the  enhancement  of  the 
protein  content.  It  is  not  so  important  to  secure  a  high  intake 
of  protein  as  to  have  proteins  of  excellent  quality.  Relatively 
small  additions  of  the  right  kind  of  protein  greatly  enhance  the 
value  of  the  proteins  of  cereals. 

133.  Soy  Beans. — The  soy  beans  have  long  been  an  important 
article  of  diet  among  the  Chinese  and  Japanese  peoples,  and  have 
been  grown  within  recent  years  somewhat  extensively  in  the 
United  States.  The  dietary  properties  of  this  seed  have  been 
studied  in  several  laboratories  (15).  The  results  show  that  this 
seed  belongs  in  the  same  class  with  peas  and  navy  beans  for  it 
contains  proteins  which  are  adequate  when  fed  at  a  plane  cor- 
responding to  17  per  cent  or  more  of  the  diet,  and  can  support 
growth  when  they  form  the  sole  protein  supply. 

When  soy  beans  are  supplemented  with  potassium  and  calcium 
salts  and  butter  fat  (fat-soluble  A)  the  nutrition  of  rats  was 


134     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

markedly  improved  as  shown  by  better  growth,  larger  litters, 
better  developed  young  and  lower  mortality  of  the  latter. 

134.  Peanut. — The  peanut  is  a  legume  seed  which  is  not  only 
eaten  in  considerable  quantities  at  times  other  than  meal-time  in 
the  roasted  state,  but  is  extensively  converted  into  peanut  butter 
in  which  form  it  is  eaten  with  bread.    Peanuts  are  grown  ex- 
tensively in  the  South  for  feeding  hogs,  but  if  fed  too  liberally 
they  produce  oily  pork.    To  avoid  this  condition  the  animals  are 
frequently  finished  on  some  other  feed  before  being  sent  to 
slaughter. 

Daniels  and  Loughlin  (16)  have  conducted  feeding  experi- 
ments with  Spanish  peanuts.  Their  results  show  that  they  have 
the  dietary  properties  common  to  seeds,  and  that  they  have  no 
marked  peculiarities.  Their  greatest  deficiencies  lie  in  their  min- 
eral content,  and  in  fat-soluble  A.  Johns  and  Jones  (17)  have 
shown  that  the  proteins  of  the  peanut  are  unusually  rich  in  lysin. 

135.  Cotton-seed  Flour. — This  is  a  product  which  is  pre- 
pared from  the  cotton  seed.    In  its  manufacture  the  oil,  hull  and 
a  considerable  amount  of  resinous  substances  are  removed.    This 
flour  has  a  nutty  flavor  and  an  effort  has  been  made  to  promote 
it  as  a  human  food.    Its  dietary  properties  have  been  studied  by 
Richardson  and  Green  (18)  and  by  Osborne  and  Mendel  (19). 
The  results  show  that  like  all  other  seeds,  the  proteins  are  com- 
plete when  fed  in  the  mixture  in  which  they  occur  in  the  seed,  and 
that  the  deficiencies  of  the  product  are  those  common  to  seeds, 
lack  of  sufficient  calcium,  sodium,  chlorin,  probably  also  of  phos- 
phorus and  fat-soluble  A.     The  proteins  of  this  flour  are  of  such 
nature  that  they  supplement  the  deficiencies  of  those  of  maize 
gluten,  a  commercial  product  obtained  in  the  manufacture  of 
corn  starch  (20).    For  this  purpose  they  are  equal  to  the  pro- 
teins of  brewer's  grains,  but  inferior  to  lactalbumin. 

136.  Cotton-seed   Products    Contain  the   Poisonous   Sul> 
stance  Gossypol. — Cotton  seed,  and  the  press  cake  obtained  in 
the  manufacture  of  cotton-seed  oil,  contains  a  poisonous  sub- 
stance to  which  Withers  and  Carruth  gave  the  name  gossypol 
(21).    The  oil  extracted  from  the  seed  either  by  pressing  or  by 
extraction  with  fat  solvents  is  also  toxic  to  animals  because  of 
the  presence  of  this  principle.    Cooking  of  the  meal  or  heating 
in  the  hot  press  method  for  extracting  the  oil  causes  a  change 
in  this  substance  which  renders  it  no  longer  soluble  in  oil  or 
ether.     It  therefore  remains  in  the  meal  (22).    While  cotton-seed 
flour  or  meal  is  a  valuable  feeding-stuff  in  animal  production,  its 


DIETARY  PROPERTIES  OF  FOODSTUFFS         135 

use  as  a  human  food  is  not  to  be  recommended  because  no  as- 
surance is  yet  offered  that  the  toxicity  of  the  products  can  be 
removed  entirely.  The  same  may  be  said  of  cotton-seed  flour. 
It  must  be  further  studied  before  it  can  be  recommended  as 
human  food. 

137.  The  Leafy  Parts  of  Plants. — These  have  dietary  prop- 
erties very  different  from  the  seeds.  The  contrast  between  the 
state  of  nutrition  which  can  be  secured  in  omnivorous  animals 
with  suitable  mixtures  of  leaf  and  seed,  as  against  mixtures  of 
seeds  alone,  even  in  complex  combinations,  was  first  pointed  out 
by  McCollum,  Simmonds  and  Pitz  (23).  It  has  not  been  found 
possible  to  secure  satisfactory  growth,  or  prolonged  well-being  in 
animals  fed  exclusively  on  seeds  and  seed  products.  The  first 
leaf  which  was  studied  was  that  of  the  alfalfa  plant,  for  the 
reason  that  the  immature  leaf  in  a  finely  ground  form  is  available 
as  a  commercial  product  known  as  alfalfa  flour. 

The  dietary  properties  of  mixtures  of  leaf  and  seed  are  well 
illustrated  by  a  series  of  nutrition  experiments  carried  out  with 
mixtures  of  seed  60  per  cent  and  alfalfa  leaf  40  per  cent.  The 
seeds  employed  included  wheat,  maize,  rolled  oat,  rice,  pea  and 
navy  bean.  The  degree  of  success  in  inducing  growth  with  these 
simple  mixtures  of  one  kind  of  seed  with  one  kind  of  leaf  is  much 
greater  than  can  ever  be  secured  with  even  such  diets  as  a  com- 
bination of  wheat,  maize,  oat,  hemp  seed  and  millet  seed  in 
equal  proportions.  The  latter  mixture  can  support  a  fair  amount 
of  growth  when  its  inorganic  deficiencies  are  corrected,  but  with- 
out additions  of  mineral  salts  almost  no  growth  can  be  secured. 
Chart  7  shows  typical  growth  records  of  animals  confined  to  diets 
of  leaf  and  seed.  Among  the  seeds  studied,  the  oat  kernel  is 
best  supplemented  by  the  alfalfa  leaf.  A  simple  mixture  of  60 
per  cent  rolled  oats  and  40  per  cent  alfalfa  leaf  induces  in  the 
rat  nearly  normal  growth  to  the  full  adult  size.  Animals  grown 
on  this  diet  have  shown  moderate  fertility  and  fair  success  in  the 
rearing  of  young.  However,  they  were  not  nourished  in  the 
optimal  manner,  for  they  fell  considerably  below  the  maximum 
capacity  of  well  nourished  animals  in  respect  to  fertility  and 
successful  rearing  of  young. 

An  examination  of  the  leaves  of  other  plants  showed  that  these 
can  in  a  general  way  be  classed  together  as  food-stuffs  of  simi- 
lar character,  since  they  resemble  one  another  more  or  less 
closely,  just  as  the  seeds  resemble  each  other  in  their  nutritive 
properties.  From  the  dietary  standpoint  the  leaf  proves  to  be 


136     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

a  very  different  thing  from  the  seed.  The  dry  leaf  usually  con- 
tains from  two  to  five  times  as  much  ash  as  does  the  seed,  and 
is  always  especially  rich  in  just  those  elements  in  which  the  seed 
is  poorest,  calcium,  phosphorus,  sodium  and  chlorin.  It  follows 
that  the  leaf  supplements  the  inorganic  deficiencies  of  the  seed. 
The  leaf  contains  in  most  cases  much  more  of  the  dietary  factor 
fat-soluble  A  than  is  found  in  any  seed.  The  leaf  as  well  as  the 
seed  contains  protein,  and  amino-acids  (24) .  The  amount  varies 
from  8  per  cent  of  protein  (N  x  6.25)  in  such  fleshy  leaves  as 
cabbage,  after  drying,  to  more  than  15  per  cent  in  dry  alfalfa 
leaf,  and  clover  leaf,  to  30  per  cent  or  more  in  the  dry  leaf  of 
the  turnip.  In  most  cases,  probably  not  all  of  the  nitrogen  in 
leaves  is  in  the  form  of  compounds  which  have  a  nutritive  value, 
but  the  leaves  appear,  from  the  data  available,  to  supplement  the 
proteins  of  the  seeds  and  to  enhance  to  some  extent  their  value. 
The  leaf  supplements  all  the  deficiencies  of  the  seed,  but  not 
necessarily  in  a  highly  satisfactory  manner  at  all  times. 

138.  Differences  in  Function  of  Leaf  and  Seed  as  a  Basis 
of  Predicting  Dietary  Properties. — It  is  interesting  to  reflect 
upon  the  reasons  why  the  leaf  of  the  plant  should  show  such 
decided  differences  in  its  nutritive  properties  as  contrasted  with 
the  seed.  A  consideration  of  the  function  of  the  two  organs  of  the 
plant  gives  the  clue  to  the  cause.  The  seed  is  composed  of  a 
germ,  which  in  most  cases  forms  but  a  small  part  of  the  entire 
seed,  together  with  a  relatively  large  endosperm.  The  germ  con- 
sists of  living  cells,  which  respire  and  which  are  capable  of  germi- 
nation (multiplication)  when  the  conditions  are  favorable.  In 
the  wheat  kernel  the  germ  constitutes  but  1.5  per  cent  of  the 
entire  kernel.  The  endosperm,  on  the  other  hand,  contains  large 
amounts  of  reserve  materials  such  as  protein,  starch,  sugars,  fats 
and  mineral  salts.  These  are  not  living  matter  but  its  by- 
products. The  endosperm  is,  therefore,  in  most  respects  compar- 
able to  a  mixture  of  purified  food  substances.  Experiments  have 
abundantly  demonstrated  that  the  endosperm  contains  relatively 
little  of  the  anti-neuritic  substance,  whereas  the  germ  is  rich  in 
this  dietary  factor.  The  last  statement  perhaps  needs  some 
qualification  in  the  light  of  recent  investigations.  Osborne  and 
Mendel  (5)  state  that  when  they  carefully  dissected  the  germ 
from  the  wheat  kernel,  and  secured  practically  pure  germ  sub- 
stance, the  product  contained  no  water-soluble  B.  The  latter 
substance  is  certainly  situated  immediately  adjacent  to  the  germ, 
for  the  germ  as  obtained  in  the  milling  process  contains  a  very 


DIETARY  PROPERTIES  OF  FOODSTUFFS        137 

large  part  of  all  that  is  found  in  the  entire  kernel.  The  dietary 
factor,  fat-soluble  A,  is  likewise  largely  localized  in  the  germ, 
where  it  is  relatively  abundant  as  compared  with  other  seed 
products.  Since  the  germ  in  most  cases  forms  such  a  small  frac- 
tion of  the  seed,  the  seed  itself  is  in  general  poor  in  this  sub- 
stance as  compared  with  the  leaf,  which  is  in  large  proportion 
made  up  of  vegetative  tissue  containing  all  the  protoplasmic 
structures  necessary  for  active  metabolism. 

The  leaf  of  the  plant,  on  the  other  hand,  is  rich  in  cells  which 
during  life  are  actively  functioning,  and  which,  with  but  few 
exceptions,  contains  but  little  reserve  food  material.  It  is  the 
laboratory  of  the  plant.  The  chlorophyll,  its  green  pigment,  en- 
ables it  to  utilize  the  energy  of  sunlight,  and  from  the  carbon 
dioxid  absorbed  from  the  air  together  with  water  and  mineral 
salts  derived  from  the  soil,  it  builds  up  protein,  starch,  sugar  and 
fat,  which  are  used  for  the  growth  of  new  plant  tissue,  or  for 
storage  in  the  seed,  tuber  or  other  organ.  The  surface  of  the 
leaf  is  a  mosaic  of  living  cells.  It  contains  all  the  complexes 
necessary  for  the  nutrition  of  animal  cells,  and  the  leaf  is  quali- 
tatively a  complete  food. 

139.  Thin  Leaves  Are  Better  Than  Thick  Ones. — From  the 
dietary  standpoint  the  quality  of  the  leaf  may  vary  to  a  con- 
siderable degree.    Some  leaves  are  thin,  cellular  structures  which 
dry  easily  when  separated  from  the  stem.    These  have  little  re- 
serve food  material  and  relatively  little  inert  tissue  of  a  skeletal 
nature.    Others,  of  which  the  cabbage  is  an  example,  have  be- 
come modified  as  storage  organs,  and  contain  a  considerable 
amount  of  reserve  food  comparable  to  that  stored  in  the  endo- 
sperm of  the  seed.     The  cabbage  leaf  also  contains  more  than 
the  average  amount  of  cellulose  and  related  substances  which 
serves   as   supporting  tissue.     The  dietary   properties   of  such 
leaves  are  modified  by  these  peculiarities  since  the  cellular  ele- 
ments are  diluted  by  the  more  inert  tissues  and  reserve  food 
substances  in  them.    The  less  a  leaf  partakes  of  the  function  of 
a  storage  tissue,  the  more  pronounced  will  be  the  leaf  quality 
as  a  food.    The  fleshy  leaves  tend  to  have  in  some  degree  the 
dietary  properties  of  the  seed,  and  in  this  respect  stand  between 
the  thin  leaves  and  the  seeds.    In  the  case  of  the  alfalfa  leaf, 
which  is  a  typical  thin  leaf  of  high  nutritive  value  as  a  forage 
plant,  the  content  of  fat-soluble  A  has  been  stated  by  Steenbock 
to  be  greater  than  its  content  of  water-soluble  B  (25) . 

140.  Tubers. — The  tubers  of  certain  plants  constitute,  after 


138     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

the  seeds,  one  of  the  most  important  classes  of  energy-yielding 
foods.  The  white  Irish  potato  is  by  far  the  most  important  of 
these  in  the  temperate  zones.  In  the  Orient  several  kinds  of 
tubers  are  widely  used  as  human  food.  An  examination  of  the 
potato  has  revealed  the  special  dietary  properties  of  this  tuber 
to  be  just  what  we  should  expect  from  its  function  as  a  storage 
organ  for  reserve  food  in  the  plant  (26).  The  function  of  the 
potato  is  two-fold,  reproduction  of  the  species  and  a  source  of 
food  supply  for  the  young  potato  plantlet  while  it  is  developing 
a  root  and  leaf  system,  which  make  it  independent  of  the  food 
in  the  old  tuber.  The  "eyes"  of  the  potato  represent  groups  of 
cells  which  are  analogous  to  the  germ  of  the  seed.  These  are  the 
locations  from  which  the  potato  sprouts  when  the  conditions  are 
favorable.  There  is  underneath  the  skin  of  the  tuber  a  layer  of 
cells  which  are  alive  and  which  respire  during  the  life  of  the 
tuber.  The  interior  of  the  potato  consists  almost  entirely  of 
water,  starch,  protein,  and  to  some  extent  of  mineral  salts.  The 
cellular  structures  in  the  interior  are  gorged  with  starch.  This 
portion  is  therefore  analogous  to  the  endosperm  of  the  seed. 
Both  are  comparable  to  a  mixture  of  purified  protein,  carbohy- 
drate and  salts,  which,  as  we  have  previously  seen,  are  not  cap- 
able of  supporting  life.  This  portion  like  the  portion  of  the  rice 
kernel  remaining  after  polishing,  is  almost  devoid  of  the  dietary 
essentials,  fat-soluble  A  and  water-soluble  B,  and  accordingly 
cannot  meet  the  nutritive  needs  of  an  animal,  even  though  it 
may  have  an  appropriate  chemical  composition. 

From  the  dietary  standpoint  the  potato  is  to  be  classed  with 
the  seeds  because  it  consists  largely  of  reserve  materials  and  of 
relatively  little  vegetative  tissues.  It  is  very  likely  that  when 
it  is  steamed  and  the  thin,  paper-like  skin  removed  without  the 
loss  of  the  cellular  layer  just  underneath,  it  will  contain  rela- 
tively more  fat-soluble  A  than  certain  of  the  cereal  grains.  Al- 
though it  has  not  been  subjected  to  experimental  test,  it  is  prob- 
able that  a  potato  pared  in  the  ordinary  way  and  the  parings  dis- 
carded, is  changed  in  its  dietary  properties  in  much  the  same 
manner  as  is  the  rice  kernel  during  polishing.  In  the  latter  case 
the  bran  layer  and  the  germ  are  both  rubbed  off,  leaving  the 
endosperm  without  the  small  quota  of  cellular  elements  it  pos- 
sessed in  the  natural  state.  The  protein  of  the  potato  is  not 
quite  so  valuable  for  the  support  of  growth  as  is  that  of  the 
cereal  grains  when  it  serves  as  the  sole  source  of  this  dietary 
factor  (26).  It  is  when  raw  an  excellent  anti-scorbutic  food. 


DIETARY  PROPERTIES  OF  FOODSTUFFS         139 

141.  There  Is  Some  Evidence  That  Potato  Nitrogen  Is 
Exceptionally    Valuable    for    "Repair." — There    have    been    a 
number  of  experiments  of  short  duration  giving  results  which 
indicate  that  in  the  human  subject  the  nitrogen  of  the  potato  is 
of  extraordinary  value  for  replacing  that  lost  through  daily  cata- 
bolism  in  the  adult   (27).     McCollum,  Simmonds  and  Parsons 
(26)  have  tested  this  question  by  comparing  with  the  protein  of 
the  cereal  grains,  the  value  of  the  nitrogen  of  the  potato  when 
this  tuber  was  supplemented  in  such  a  manner  as  to  make  good 
all   its   dietary   deficiencies,   except  protein.     The   experiments 
involved  growth  tests  in  the  young  rat.    The  results  show  be- 
yond doubt  that  potato  nitrogen  falls  considerably  below  the 
value  for  growth  possessed  by  individual  cereal  grains,  when 
each  of  these  serves  as  the  sole  source  of  supply  of  the  digestion 
products  of  protein. 

The  experiments  which  have  been  reported  of  the  maintenance 
of  rats  on  potato  protein  support  the  conclusion  of  Rose  and 
Cooper  (27) ,  that  this  nitrogen  has  a  high  biological  value  for  the 
replacement  of  the  tissue  substance  lost  in  endogenous  metabol- 
ism. This  observation  has  a  bearing  on  the  question  whether  the 
processes  of  repair  can  be  carried  on  with  certain  chemical  com- 
plexes absent  from  the  diet,  which  are  essential  when  growth 
takes  place  involving  the  formation  of  new  tissues. 

142.  Fleshy  Roots. — These  are  in  a  general  way  similar  to 
the  potato  with  respect  to  the  relation  between  dietary  properties 
and  biological  function.    The  roots  we  employ  as  foods  are  those 
which  are  highly  modified  as  storage  organs,  and  resemble  the 
potato  in  possessing  a  very  high  water  and  starch  content  and 
but  very  little  protein.    In  the  case  of  the  sugar  beet,  the  sugar 
replaces  starch  in  a  great  measure.    As  in  the  potato  there  is  a 
cellular  layer  at  the  periphery,  but  the  interior  is  loaded  with 
reserve  food-stuffs.    Appropriate  feeding  tests  have  shown  that 
the  properties  of  the  beet  resemble  those  of  the  seed  and  tuber 
rather  than  those  of  the  leaf  (28).    The  fleshy  roots,  the  dasheen 
and  sweet  potato,  have  an  inorganic  content  which  resembles 
that  of  the  seeds  in  a  general  way,  so  that  an  inspection  of  the 
analytical  data  relating  to  the  composition  of  the  ash  of  seeds, 
tubers  and  roots  gave  no  promise  that  combinations  in  diets  of 
seeds  with  either  of  the  latter  classes  of  food-stuffs  would  correct 
the  inorganic  deficiencies  of  the  former.    Feeding  tests  in  which 
the  seeds  and  tubers  or  roots  have  been  combined  and  so  sup- 
plemented with  purified  protein,  and  butter  fat  (fat-soluble  A) 


140     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

that  all  the  deficiencies  of  the  mixture  except  the  inorganic  were 
made  good,  have  given  interesting  results.  The  mineral  elements 
derived  from  the  natural  foods  in  the  mixtures,  are  not  furnished 
in  proportions  to  meet  the  nutritive  needs  of  a  growing  animal. 
It  is  the  low  content  of  calcium,  phosphorus,  sodium  and  chlorin 
which  is  responsible  for  the  failure  of  the  animals,  for  when  these 
are  added  along  with  protein  and  fat-soluble  A,  growth  proceeds 
in  the  normal  trend. 

In  the  dry  state,  therefore,  the  fleshy  roots  resemble  the  seeds 
in  food  value.  There  is,  however,  one  difference  which  should  be 
mentioned.  Like  the  potato  and  unlike  the  seeds  the  fleshy  roots 
contain  a  large  part  of  their  nitrogen  in  forms  which  are  chemi- 
cally much  simpler  than  protein.  A  part  of  this  nitrogen  is 
actually  in  the  forms  of  digestion  products  of  protein,  and  these 
are  of  the  same  value  as  protein.  This  value  depends  entirely 
on  the  presence  of  a  complete  list  of  amino-acids  necessary  for 
the  construction  of  body  proteins,  and  on  the  proportions  in  which 
they  occur.  There  is  always  a  part  of  the  nitrogen  in  the  form 
of  other  complexes  which  have  no  nutritive  value. 

A  study  of  the  carrot  has  been  made  by  the  biological  method 
by  Denton  and  Kohman  (29).  Their  results  show  that  it  was 
possible  to  maintain  young  rats  for  some  weeks  on  a  diet  com- 
posed exclusively  of  carrots,  supplemented  with  sodium  chlorid 
and  a  calcium  salt,  but  the  animals  were  not  able  to  grow.  They 
found  it  necessary  to  supplement  the  protein,  and  augment  the 
fat-soluble  A  content  before  the  rat  was  able  to  maintain  growth 
even  in  an  approximately  normal  manner. 

143.  Great  Differences  Are  Found  in  the  Fat-Soluble  A 
Content  of  Different  Kinds  of  Roots. — Steenbock  and  Gross 
(28)  have  studied  the  more  important  fleshy  roots  used  as  food 
in  the  United  States  for  man  or  animals,  especially  with  respect 
to  their  content  of  fat-soluble  A.  They  adopted  the  standard 
method  of  McCollum  and  Davis,  feeding  a  purified  food  mix- 
ture supplemented  with  varying  amounts  of  a  natural  food  as  a 
source  of  the  dietary  essential  in  question.  Their  results  are  of 
unusual  interest  for  they  showed  that  carrots  and  sweet  potato, 
both  of  which  contain  much  yellow  pigment,  are  far  better  sources 
of  fat-soluble  A  than  are  any  of  the  roots  which  do  not  have  a 
yellow  color.  Rutabega,  dasheen,  red  beet,  parsnip,  potato,  man- 
gle and  sugar  beet  appear  from  their  results  to  contain  practically 
none  of  this  substance.  They  were  inclined  to  the  belief  that  this 
dietary  essential  is  associated  in  foods  with  the  yellow  pigment. 


DIETARY  PROPERTIES  OF  FOODSTUFFS        141 

This  idea  rested  on  insufficient  evidence,  as  will  be  shown  in 
Chapter  XII,  where  the  literature  relating  to  this  subject  will  be 
discussed.  The  roots  so  far  as  they  have  been  studied,  appear 
to  be  effective  sources  of  water-soluble  C. 

144.  Fruits. — From  the  results  of  chemical  analysis   fruits 
appear  to  be  closely  comparable  in  their  composition  to  the  fa- 
miliar vegetables  such  as  the  tubers  and  roots.    They  all  con- 
tain much  water,  and  varying  amounts  of  sugars,  and  are  rela- 
tively insignificant  as  sources  of  protein  or  fat.    They  are  much 
more  attractive  to  the  palate  than  are  most  of  the  vegetables. 
They  enjoy  the  popular  reputation  of  possessing  mild  laxative 
properties,  and  tend  to  increase  elimination  by  virtue  of  their 
mild  diuretic  qualities,  part  of  which  are  due  to  the  extra  water 
consumption,  and  part  to  the  action  of  certain  salts  of  organic 
acids  they  contain. 

Fruit  juices  or  the  edible  parts  of  fruits  differ  from  the  cereal 
grains,  and  resemble  in  a  very  important  respect  the  vegetables, 
which  are  morphologically  tubers  or  roots.  There  is  an  excess 
of  basic  radicles  which  renders  their  ash  alkaline,  whereas  most 
seeds  give  an  acid  ash.  Meats  are  also  of  acid  character.  The 
meat  and  bread  portion  of  our  diet,  when  oxidized  in  metabolism 
leads  to  the  formation  of  an  excess  of  acid  over  base-forming 
substances.  It  is  now  a  well  established  fact  that  a  certain 
alkali  reserve  in  the  blood  is  essential  to  maintain  its  capacity 
to  carry  carbon  dioxid  to  the  lungs  for  elimination,  and  that  a 
common  pathological  condition,  acidosis,  exists  in  which  this 
reserve  falls  below  normal.  This  forms  sound  reason  why  the 
addition  of  fruits  and  vegetables  to  the  diet  tends  to  the  estab- 
lishment of  a  proper  acid-base  equilibrium  in  the  various  fluids 
of  the  body. 

The  fruits  differ  from  the  leafy  vegetables  in  containing  little 
calcium.  They  resemble  the  tubers  and  roots  insofar  as  they 
do  not  tend  to  supplement  the  deficiencies  of  seed  or  meat  prod- 
ucts in  this  respect. 

145.  Citrus  Fruits  Have  Long  Been  Valued  as  Anti-scor- 
butic Foods. — Certain  fresh  fruits,  especially  those  of  the  citrus 
group,  which  includes  the  lemon,  orange,  lime  and  grapefruit, 
have  long  enjoyed  popularity  for  their  potency  in  preventing 
scurvy.    This  has  been  shown  in  recent  investigations  to  be  well 
founded  and  to  depend  upon  the  presence  of  a  specific  chemical 
substance,  water-soluble  C.  Wide  differences  in  the  value  of  dif- 
ferent fruits  for  this  purpose  have  been  shown  by  investigations 


142     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

relating  to  scurvy.  The  content  of  the  anti-neuritic  substance, 
water-soluble  B,  of  several  fruits  has  been  studied  by  Osborne 
and  Mendel,  and  by  Byfield,  Daniels  and  Loughlin  (30) .  Their 
findings  indicate  that  the  anti-neuritic  value  of  orange  juice  is 
about  the  same  as  that  of  an  equal  volume  of  milk.  Orange 
juice  to  the  extent  of  55  c.c.  per  100  grams  of  food  mixture  was 
not  sufficient  to  furnish  the  optimal  amount  of  the  factor  B,  but 
75  c.c.  seemed  satisfactory.  Lemon  juice  was  comparable  in  this 
respect  to  orange  juice.  Ten  c.c.  of  juice  per  day  afforded  suffi- 
cient water-soluble  B  to  support  growth  at  the  normal  rate 
when  added  to  an  otherwise  adequate  diet.  Grapefruit  was  also 
found  to  contain  the  anti-neuritic,  water-soluble  B.  McCollum 
and  Simmonds  have  found  orange  juice  to  contain  demonstrable 
amounts  of  fat-soluble  A  (31). 

Commercial  grape  juice,  and  fresh  apple  juice  were  found  in- 
ferior to  the  citrus  fruits  as  a  source  of  water-soluble  B.  Pears 
resemble  apples  in  this  respect,  but  prunes  seemed  superior  to 
either.  The  fruit  juices  tested  by  Osborne  and  Mendel  did  not 
show  appreciable  amounts  of  fat-soluble  A  (30). 

146.  The  Banana. — The  banana  has  been  studied  as  food  for 
the  rat  by  Benedict  and  Sugiura  (32)  and  as  a  nutrient  substance 
for  the  banana  fly,  Drosophila  ampelophila,  by  Loeb  and  North- 
rup  (33).  The  former  investigators  found  it  deficient  in  pro- 
tein, and  in  water-soluble  B.  This  last  observation  is  remark- 
able since  banana  constituted  about  80  per  cent  of  their  experi- 
mental diet.  Their  studies  also  seem  to  verify  the  generalization 
of  Steenbock  and  Gross  (28)  that  this  yellow  fruit  contains  more 
fat-soluble  A  than  do  fruits  in  general,  or  more  than  the  roots 
and  tubers  not  so  pigmented.  Benedict  and  Sugiura  also  stated 
that  in  their  experience  casein  proved  a  much  more  effective  sup- 
plement to  the  banana  than  washed  and  dialyzed  beef.  In  their 
experiments  the  banana  supplemented  with  casein,  and  a  source 
of  water-soluble  B  (yeast  or  carrot  extract)  proved  inadequate 
for  the  production  of  milk  by  lactating  rats.  The  failure  lay  in 
the  quality  of  the  milk  and  not  in  the  quantity,  since  the  mothers 
failed  to  succeed  with  both  small  and  large  litters. 

Loeb  and  Northrup  found  sterile  banana  inadequate  for  the 
nutrition  of  the  banana  fly,  but  banana  cultured  with  yeast  was 
satisfactory  (33).  The  interpretation  placed  upon  this  observa- 
tion is  that  the  yeast  cell  produces  synthetically  some  substance 
or  substances,  not  present  in  the  banana,  but  necessary  for  the 
nutrition  of  the  fly.  The  nature  of  this  relationship  between  the 


DIETARY  PROPERTIES  OF  FOODSTUFFS         143 

development  of  yeast  and  the  improvement  of  the  nutrition  of 
this  insect  is  not  clear. 

147.  Nuts. — Nuts  have  not  been  extensively  studied  by  the 
biological  method.    Little  can  be  said  of  their  dietary  properties 
other  than  what  can  be  deduced  from  their  chemical  composition 
and  from  their  function  in  the  plant  from  which  they  are  de- 
rived (34).    With  the  exception  of  the  chestnut,  nuts  are  very 
rich  in  protein,  and  fat,  and  poor  in  carbohydrates.    The  edible 
portions  of  several  of  the  more  highly  prized  nuts  contain  the 
following  amounts  of  protein:  Almond  21  per  cent;  beech-nut  22 
per  cent;  brazil  nut  17  per  cent;  chestnut  6.2  per  cent;  pecan 
11  per  cent;  walnut  18.5  per  cent.    The  fat  content  of  these  nuts 
is  on  an  average:  Almond  55  per  cent;  beech-nut  57  per  cent; 
brazil  nut  67  per  cent;  chestnut  6.2  per  cent;  pecan  71  per  cent; 
walnut  64  per  cent.    The  digestible  carbohydrate  of  most  nuts  is 
very  small.    The  chestnut  is  unique  among  the  ordinary  nuts  in 
that  it  contains  about  45  per  cent  of  starch  and  but  little  fat. 
Feeding  studies  have  shown  that  several  nuts  have  essentially 
the  same  dietary  properties  as  seeds  in  general  (34) . 

The  flavors  of  nuts  are  especially  attractive,  and  they  form  a 
group  of  highly  desirable  food-stuffs.  They  are,  however,  the 
seeds  of  plants  and  one  would  predict  that  their  dietary  prop- 
erties are  not  such  as  to  make  them  effective  supplements  for 
the  cereals,  legume  seeds,  tubers,  roots  or  fruits,  except  in  re- 
spect to  the  protein  factor.  A  diet  composed  of  such  combina- 
tions of  food  may  be  chemically  balanced  so  far  as  analysis  can 
show,  but  be  decidedly  defective  in  other  respects. 

148.  Animal   Tissues. — These    include   veal,   chicken,   beef, 
pork,  lamb,  etc.    They  must  be  differentiated  into  two  groups, 
on  the  basis  of  whether  they  are  glandular  organs  such  as  the 
liver  and  the  kidney  or  highly  specialized  tissue  such  as  the 
muscles  or  connective  structures.    It  seems  certain  that  we  are 
justified  in  generalizing  to  the  extent  of  saying  that  those  organs 
which  are  the  seat  of  metabolic  activity  of  the  type  concerned 
with  the  elaboration  of  secretions  or  intermediate  or  end  prod- 
ucts of  metabolism  are  more  complete  foods  than  are  those  char- 
acterized by  inertness  such  as  are  the  supporting  and  the  con- 
tractile tissues.    One  would  expect,  in  the  light  of  the  marked 
differences  in  the  dietary  properties  of  the  vegetative  parts  of 
plants  as  contrasted  with  the  storage  tissues  to  find  comparable 
differences  in  the  nutritive  value  of  animal  tissues  having  differ- 
ent functions.    Experiment  has  shown  this  to  be  warranted. 


144     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Watson  (35)  restricted  birds  to  an  exclusive  diet  of  muscle 
meat,  and  observed  profound  pathological  changes,  especially 
nervous  disturbances  and  paralysis  (poly neuritis) ,  hypertrophy 
of  the  thyroid  gland  to  the  extent  of  ten  times  its  normal  size, 
and  hypertrophy  of  the  parathyroids.  He  also  studied  the  effects 
on  rats  of  an  exclusive  diet  of  horse  and  of  beef  muscle  (36)  and 
found  that  not  only  did  young  animals  die  but  that  the  older 
ones  were  distinctly  inferior  in  their  ability  to  produce  and  rear 
young. 

149.  Osborne  and  Menders  Studies  on  the  Vitamin  Con- 
tent of  Animal  Tissues. — Osborne  and  Mendel  (37)  have  shown 
that  muscle  tissue  is  very  deficient  in  the  anti-neuritic  factor, 
water-soluble  B,  and  in  the  anti-ophthalmic  factor,  fat-soluble 
A  and  that  it  contains  but  very  little  of  the  anti-scorbutic  factor, 
water-soluble  C.     Meat  extracts  were  also  deficient  in  these 
respects. 

In  marked  contrast  to  the  results  with  muscle  tissues  are  those 
obtained  with  the  glandular  organs.  McCollum  and  Davis  (38) 
showed  that  an  ether  extract  of  pig  kidney  or  of  codfish  testicles 
is  a  good  source  of  fat-soluble  A.  They  also  showed  that  heart 
muscle  is  decidedly  deficient  in  this  substance  as  compared  with 
kidney.  These  results  for  heart  and  kidney  were  verified  by  Os- 
borne and  Mendel  (37).  These  authors  also  showed  that  liver 
is  a  good  source  of  fat-soluble  A,  and  water-soluble  B.  The  liver, 
when  fresh,  is  rich  in  anti-scorbutic  properties  (39).  Osborne 
and  Mendel  have  found  that  the  proteins  of  muscle,  liver,  kid- 
ney and  brain  are  complete  as  sources  of  amino  acids  for  the 
support  of  growth  when  each  serves  as  the  sole  source  of  protein 
in  the  diet. 

These  findings  are  in  harmony  with  the  studies  of  Cooper  (40) , 
who  made  a  comparative  study  of  the  relative  values  of  a  series 
of  food-stuffs  for  the  prevention  of  polyneuritis  in  birds.  The 
results  were  expressed  in  terms  of  grams  of  fresh  substance  per 
day  necessary  to  prevent  the  development  of  the  disease.  These 
values  are  as  follows:  Ox  muscle,  20;  ox  cardiac  muscle,  5;  ox 
cerebrum,  6;  ox  cerebellum,  12;  ox  liver,  3;  sheep  cerebrum,  8- 
15;  fish  muscle,  more  than  10;  egg  yolk,  3;  cow's  milk,  more  than 
35;  cheese,  more  than  8. 

As  a  source  of  protein  for  the  support  of  growth  the  kidney  is 
greatly  superior  to  muscle  tissue.  Liver  appears  to  fall  between 
these  in  its  value  as  a  source  of  amino  acids. 

150.  Muscle  Meats  Differ  Greatly  in  Their  Dietary  Prop- 


DIETARY  PROPERTIES  OF  FOODSTUFFS        145 

erties  from  the  Glandular  Organs. — In  meat  eating  of  the  type 
so  common  in  America,  in  which  ham,  steaks,  roasts,  chops,  and 
other  cuts  which  are  derived  from  muscle,  are  almost  exclu- 
sively used,  the  only  important  supplementing  effect  of  meat  on 
the  remainder  of  the  diet  lies  in  the  enhancement  of  the  protein 
and  in  the  increase  in  the  phosphorus  content.  When  glandular 
organs  are  eaten,  these  add  considerable  amounts  of  fat-soluble 
A  and  water-soluble  B,  but  when  cooked,  no  water-soluble  C. 
In  general  we  eat  so  little  of  the  glandular  organs  that  this  source 
of  the  uncharacterized  factors  is  nearly  negligible. 

The  liver  and  kidney  are,  however,  so  exceptionally  valuable 
in  enhancing  the  biological  values  of  certain  cereal  grains,  that 
they  may  well  find  a  regular  place  in  the  diet  under  certain  con- 
ditions where  it  is  desired  to  have  a  low  protein  intake  of  excep- 
tionally high  quality  (41). 

151.  Animal  Fats. — These  have  been  studied  to  determine 
their  value  as  a  source  of  fat-soluble  A.  This  substance,  it  will 
be  remembered,  is  especially  abundant  in  butter  fat,  egg  yolk  fat 
and  in  the  leaves  of  certain  plants.  McCollum  and  Davis  (42) 
and  also  Osborne  and  Mendel  (43)  found  that  lard  had  no  ap- 
preciable growth-promoting  properties  when  added  to  a  diet 
complete  except  for  fat-soluble  A.  Osborne  and  Mendel  showed 
that  cod  liver  oil  is  an  excellent  source  of  fat-soluble  A.  They 
examined  the  more  liquid  portion  of  beef  fat  and  found  that  it 
contained  in  demonstrable  amount  the  dietary  factor  in  question, 
whereas  the  unfractionated  fat  was  very  poor  in  it  (44) .  Halli- 
burton and  Drummond  (45)  obtained  similar  results  in  their 
study  of  the  nutritive  properties  of  various  kinds  of  margarines. 

Recently  Daniels  and  Loughlin  (46)  have  presented  data  which 
indicate  that  some  samples  of  lard  contain  demonstrable  amounts 
of  fat-soluble  A.  For  periods  of  five  months  they  were  able  to 
secure  growth  in  young  rats  with  diets  containing  28  per  cent 
of  lard  as  a  source  of  this  dietary  essential.  In  other  experi- 
ments where  but  21  per  cent  was  used  the  animals  were  not 
able  to  grow  after  two  months.  The  findings  in  our  own  labora- 
tory indicate  that  there  was  probably  a  certain  amount  of  fat- 
soluble  A  in  their  ration  derived  from  the  extract  of  wheat  germ 
added  for  the  purpose  of  supplying  water-soluble  B. 

These  results  are  not  to  be  interpreted  as  indicating  that  lard 
is  in  any  sense  comparable  as  a  source  of  this  dietary  essential 
to  the  fats  of  milk,  egg  yolk  or  the  leafy  vegetables.  It  is  doubt- 
less true  that  the  body  fats  of  all  animals  which  have  been  fed 


146      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

liberal  amounts  of  a  forage  plant  will  contain  sufficient  amounts 
of  fat-soluble  A  to  make  possible  a  short  positive  demonstration 
of  its  presence.  It  should  be  kept  in  mind  that  when  questions 
relating  to  the  adequacy  of  human  dietaries  are  to  be  judged 
from  the  results  of  animal  experiments,  the  content  of  the  mate- 
rial fed,  and  the  life  history  of  the  animals  must  be  taken  into 
consideration.  The  dietary  history  of  the  animals  from  which 
came  the  fat  used  in  feeding  should  be  considered,  in  order  to 
make  it  clear  whether  the  samples  examined  were  typical.  It 
seems  that  the  products  used  by  Daniels  and  Loughlin  were  not 
representative  of  lards  in  general. 

152.  The  Biological  and  Nutritive  Properties  of  Muscle 
Tissue. — The  muscle  tissue  of  an  animal  consists  of  highly  spe- 
cialized substance  the  chief  function  of  which  is  to  do  mechanical 
work  through  contraction.  In  this  process  it  derives  the  energy 
from  glucose  or  from  fat.  It  is,  in  addition,  a  storage  organ  for 
glycogen,  or  so-called  animal  starch,  and  for  fat.  It  contains 
but  little  of  cellular  structures  which  are  the  seat  of  chemical 
activity,  such  as  are  exhibited  by  the  glandular  organs.  Chemi- 
cal analysis  shows  muscle  to  consist  for  the  most  part,  aside  from 
the  reserve  food-stuffs,  of  water,  protein  and  salts.  The  gland- 
ular organs  yield  relatively  much  nucleic  acid  while  the  muscle 
yields  but  little.  The  inorganic  content  of  muscle  resembles  that 
of  the  seeds  of  plants  rather  than  that  of  the  leaves.  Its  ash  is 
highly  acid,  whereas  that  of  leaves  is  highly  alkaline.  Muscle 
is,  however,  very  poor  in  magnesium  as  compared  with  any  vege- 
table food  materials,  is  rich  in  phosphorus,  and  contains  much 
more  iron.  Since  it  is  also  very  poor  in  fat-soluble  A,  it  does 
not  supplement  the  seeds  in  any  appreciable  degree  except  with 
respect  to  the  protein  factor. 

It  follows,  therefore,  that  we  should  not  expect  to  secure 
growth  and  normal  nutrition  with  mixtures  of  seeds  and  muscle 
meats.  Experimental  trials  have  shown  that  this  is  the  case. 
Such  mixtures  require  supplementing  with  respect  to  calcium, 
sodium  and  chlorin,  just  as  do  seed  mixtures  alone.  In  most 
instances  such  mixtures  will  also  require  to  be  supplemented  with 
fat-soluble  A  before  they  will  constitute  diets  which  are  satis- 
factory for  normal  growth  and  for  the  support  of  females  during 
gestation  and  nursing  of  the  young.  It  is  doubtless  possible 
that  with  yellow  maize  or  millet  seed  in  the  diet  in  very  liberal 
amount,  this  factor  may  be  of  sufficient  quality  to  permit  over  a 
considerable  period  of  time  of  apparently  normal  functioning. 


DIETARY  PROPERTIES  OF  FOODSTUFFS        147 

It  seems  highly  probable,  however,  that  even  with  diets  of  this 
special  selection,  animals  would  be  benefited  by  a  more  liberal 
intake  of  fat-soluble  A.  Meat  and  seed  diets  can  be  supplement- 
ed with  liberal  amounts  of  the  edible  leaves,  so  as  to  make  good 
their  dietary  deficiencies  to  an  extent  which  will  bring  about  ap- 
proximately normal  nutrition  provided  the  right  selection  of  seeds 
and  leaves  is  made.  Our  knowledge  in  this  direction  is  still  very 
fragmentary. 

The  glandular  organs  are  not  superior  to  the  muscle  tissues  in 
their  mineral  content.  They  are  vastly  more  satisfactory  as 
sources  of  protein,  fat-soluble  A,  water-soluble  B  and  water- 
soluble  C. 

153.  Dietary  Habits  of  Carnivorous  Man  and  Animals. — 
The  pronounced  deficiencies  of  muscle  tissue  as  a  food-stuff  nat- 
urally suggest  the  question  as  to  the  reason  for  the  success  of  the 
nutrition  of  the  strictly  carnivorous  animals.    This  explanation 
is  found  in  the  selection  these  animals  make  of  the  parts  of  their 
prey.    The  carnivorae  are  all  fond  of  blood,  and  it  is  their  cus- 
tom to  open  the  jugular  veins  of  a  freshly  killed  animal  and  suck 
blood  as  long  as  it  will  flow.    After  blood,  the  glandular  organs 
appeal  most  strongly  to  them  in  temperate  and  tropical  regions, 
but  in  the  Arctic  the  second  choice,  or  even  the  first  may  be  fat, 
depending  on  the  previous  state  of  nutrition  of  the  animal.     If 
it  has  recently  ingested  liberal  amounts  of  protein  it  may  take 
only  fat  from  the  victim  serving  as  its  next  repast.    This  is  said 
to  happen  frequently  in  the  case  of  polar  bears.    A  seal  is  often 
found  by  explorers,  stripped  of  its  fat  but  otherwise  untouched. 
The  demands  for  energy  are  so  great  in  these  bears  as  to  make  it 
necessary  to  consume  fat  frequently  and  in  large  amounts.    Since 
the  protein  metabolism  is  of  much  smaller  magnitude,  meat  of 
either  the  glandular  or  muscle  type  may  be  taken  at  much  longer 
intervals. 

When  the  American  Indians  subsisted  on  the  bison  of  the 
great  plains,  bone  marrow  was  regarded  as  a  morsel  of  the  great- 
est delicacy,  and  this  is  also  true  to-day  of  the  inhabitants  of 
Arctic  America.  So  far  as  possible  blood  is  either  used  fresh  or 
is  preserved  for  making  soup.  Most  of  the  Asiatic,  and  some  of 
the  European  peoples  have  no  abhorrence  for  blood  as  a  food. 
In  China  blood  is  regularly  sold  as  food,  and  in  Europe  blood 
sausage  is  a  common  article  of  diet. 

154.  Certain   Strictly   Carnivorous    Diets   Are   Successful 
with  Laboratory  Animals. — When  we  make  a  mixture  of  equal 


148     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

parts  of  blood  and  muscle  and  confine  young  rats  to  it  they  may 
grow  in  a  fairly  normal  manner,  whereas  with  either  of  these 
two  tissues  alone  they  will  suffer  disaster  (47).  Mixtures  of 
blood,  liver  or  kidney,  muscle  and  bone  may  be  so  selected  as 
to  proportions  as  to  make  a  very  satisfactory  diet  (31).  Here, 
again,  the  controlled  experiment  of  the  laboratory  reveals  the 
secret  of  success  in  the  nutrition  of  a  class  of  animals  whose  ex- 
cellent physical  development  on  a  diet  derived  solely  from  ani- 
mal tissues  has  often  been  interpreted  as  signifying  that  meat, 
in  the  general  sense  in  which  we  use  this  term,  is  a  complete 
food  and  one  of  exceptional  value  for  promoting  vigor.  The 
meat-eating  of  the  peoples  of  the  temperate  regions  of  America 
is  limited  essentially  to  the  consumption  of  muscle  tissue.  In 
dietary  properties  this  is  the  poorest  part  of  the  carcass.  Those 
who  take  a  varied  diet  in  which  cereals  and  potatoes  form  the 
most  prominent  sources  of  energy,  are  guided  by  their  sense  of 
taste  to  select  muscle  meats  rather  than  other  meats  superior 
in  dietary  value. 

155.  The  Successful  Rearing  of  Young  Lions. — An  inter- 
esting example  of  the  importance  of  making  a  proper  choice  of 
animal  parts  in  order  to  make  a  complete  diet,  is  afforded  by 
the  experience  of  those  who  have  attempted  to  rear  young  lions 
in  captivity.     With  few  exceptions  in  the  past  such  attempts 
have  proven  failures,  since  the  animals  developed  rickets.     If 
they  survived  they  were  so  deformed  as  to  be  unfit  for  exhibition 
purposes.    In  recent  years  in  at  least  two  zoological  gardens 
these  animals  are  now  reared  successfully.    A  young  lion  cannot 
grow  normally  on  a  piece  of  muscle  meat  with  a  large,  hard  bone 
attached.    In  many  cases  the  large  bones  given  them  were  so 
hard  that  little  could  be  gnawed  therefrom.    When  these  animals 
are  fed  with  liver,  fat,  and  bone  of  a  type  which  they  can  eat 
in  considerable  amount  without  danger  of  choking,  and  when 
their  diet  is  varied  frequently  with  small  animals  which  can  be 
consumed  entirely,  such  as  rabbits  or  pigeons,  they  grow  up 
strong  and  beautiful. 

156.  Dietary  Properties  of  Muscle  and  Those  of  Glandular 
Organs    Contrast    Sharply. — Too   much    emphasis    cannot    be 
placed  upon  the  dietary  deficiencies  of  muscle  meats  such  as 
beefsteak,  ham,  roasts  and  others  of  this  class.    Scarcely  any- 
thing more  detrimental  could  be  done  to  a  young  animal  than  to 
restrict  it  for  a  few  weeks  to  a  diet  exclusively  derived  from  such 
meats.    It  is  imperative  that  we  understand  the  marked  differ- 


DIETARY  PROPERTIES  OF  FOODSTUFFS        149 

ences  between  our  kind  of  meat  eating,  which  calls  only  for  meats 
of  the  muscle  class,  and  that  of  the  successfully  nourished  car- 
nivorous animals.  The  latter  eat  liberally  of  several  parts  of 
the  bodies  of  their  prey  which  have  much  more  satisfactory 
dietary  properties  than  the  muscle  tissues,  and  thus  secure  a 
properly  balanced  diet.  The  glandular  organs  are  much  better 
constituted  as  food,  than  are  the  muscles,  and  these  should  be 
selected  oftener  than  they  are  at  present  in  America.  The  liver, 
kidney,  sweetbread,  etc.,  are  not  complete  foods  in  the  sense  that 
they  furnish  the  proper  amounts  of  each  of  the  dietary  essen- 
tials for  the  nutrition  of  the  body,  but  they  are  among  those 
best  constituted,  and  are  vastly  superior  to  any  other  animal 
tissues.  The  glandular  structures  are,  like  muscle,  lacking  in 
calcium,  and  should  always  be  supplemented  with  some  food 
rich  in  this  element.  This  is  the  only  deficiency  in  this  class 
of  foods  of  animal  origin.  Meats  of  all  kinds  have  a  very  great 
value  for  enhancing  the  values  of  proteins  of  the  cereal  grains. 

157.  Milk. — This  is  the  most  satisfactory  single  article  of 
food  which  is  suitable  for  consumption  by  man.  It  is  not  an 
ideal  food  when  taken  over  a  long  period  as  the  sole  source  of 
nutriment,  but  is  the  best  one  with  which  nature  has  provided 
us.  It  is  the  one  food  for  which  there  is  no  effective  substitute. 

Milk  is  a  very  effective  food  for  supplementing  the  deficiencies 
of  other  substances  such  as  the  cereal  grains,  tubers  and  fleshy 
roots  (48) .  It  is  rich  in  both  calcium  and  phosphorus,  and  many 
vegetable  foods  are  relatively  poor  in  both  these  elements,  espe- 
cially the  former.  In  fact,  there  are  but  two  classes  of  foods 
which  are  relatively  rich  in  calcium,  the  principal  element  in  lime, 
and  a  prominent  constituent  of  the  substance  of  bone.  These 
are  the  milks  of  various  animals  and  the  leafy  vegetables.  All 
other  kinds  of  foods  fall  below  the  nutritive  requirements  of  man 
and  animals  in  this  substance.  The  body  is  very  sensitive  to 
deviations  from  the  optimal  concentration  of  calcium  in  the  food, 
and  serious  damage  may  easily  result  to  the  bone  structures  if 
the  diet  is  not  properly  constituted  with  respect  to  this  substance. 
158.  Milk  Is  Deficient  in  Iron. — The  most  marked  deficiency 
of  milk  is  in  its  content  of  iron,  which  is  very  low.  The  new- 
born mammal  is  provided  with  a  store  of  this  element  in  its  tis- 
sues, sufficient  to  tide  it  over  the  period  while  it  is  on  an  exclusive 
milk  diet,  but  if  a  child  were  confined  too  long  to  milk  as  its  sole 
food  it  would  suffer  from  anemia  for  lack  of  iron. 
Milk  is  a  water  rich  food,  containing  about  87  per  cent  of 


150     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

water  and  13  per  cent  of  dissolved  substances  consisting  for  the 
most  part  of  proteins,  milk  sugar  and  fats  (49).  It  is  too  bulky 
to  be  satisfactory  as  the  sole  food  for  the  adult,  because  of  the 
difficulty  of  taking  a  sufficient  amount  to  cover  the  energy  re- 
quirements. It  is,  therefore,  to  be  valued  essentially  as  a  food 
for  supplementing  other  foods  and  for  specifically  correcting  their 
deficiencies.  The  striking  fact  brought  out  by  modern  nutri- 
tion investigations  is  that  most  animal  and  vegetable  foods  are 
singly  or  collectively  faulty  in  sufficient  degree  to  interfere  se- 
riously with  the  physical  development  of  the  young  and  to  lead 
to  early  deterioration  of  the  adult.  The  most  important  consid- 
eration to  be  kept  in  mind  is,  therefore,  the  selection  of  food  so 
as  to  compensate  the  deficiencies  of  one  article  by  those  of  an- 
other and  thus  make  a  properly  balanced  dietary.  For  this 
purpose  milk  is  truly  the  ideal  food.  The  property  of  enhancing 
all  the  deficiencies  of  cereal  grains,  legume  seeds,  tubers,  roots 
and  muscle  meats,  is  possessed  only  by  milk  and  the  leafy  vege- 
tables, and  for  this  reason  McCollum  proposed,  in  1918,  that  in 
order  to  make  these  two  classes  of  foods  stand  out  in  importance 
as  they  deserve  to  do,  they  should  be  designated  "protective 
foods"  (50). 

The  supplementary  value  of  milk  for  other  foods  depends  upon 
its  unique  calcium  content,  on  the  quality  of  its  proteins,  espe- 
cially their  special  fitness  for  completing  the  amino-acid  quota 
and  balancing  the  same,  in  vegetable  foods  of  the  storage  tissue 
class,  and  on  the  quality  of  its  fat. 

It  is  of  great  interest  that  recent  investigations  which  were 
sufficiently  extensive  to  make  them  conclusive,  have  shown  that 
the  proteins  of  muscle,  liver  and  kidney,  are  in  general  more 
valuable  for  enhancing  the  values  of  cereal  and  legume  seeds 
than  are  the  proteins  of  milk.  It  is  only  in  this  respect,  how- 
ever, that  the  animal  tissues  surpass  milk  (51). 

159.  The  Fats  of  Milk  a  Good  Source  of  Fat-Soluble  A.— 
The  fats  of  milk  are  the  most  important  source  in  the  American 
and  European  diet  of  the  dietary  essential  fat-soluble  A.    This, 
as  has  been  pointed  out,  is  not  abundant  in  any  seeds,  tubers  or 
roots,  as  compared  with  the  amounts  of  it  contained  in  butter 
fat  of  good  quality.    This  is  the  anti-ophthalmic  substance,  fat- 
soluble  A.    It  is  essential  for  growth  or  for  normal  maintenance. 
This  substance  will  be  considered  more  in  detail  in  a  later  chap- 
ter in  connection  with  the  deficiency  diseases. 

160.  Milk  Is  Frequently  Soured  to  Preserve  it  from  Un- 


DIETARY  PROPERTIES  OF  FOODSTUFFS        151 

wholesome  Decomposition. — Milk  is  not  only  the  most  perfect 
human  food  but  is  likewise  an  unsurpassed  nutrient  medium  for 
the  growth  of  bacteria.  Hence  it  is  very  liable  to  become  un- 
wholesome through  the  agency  of  microorganisms  unless  it  is 
properly  handled.  In  hot  countries  and  among  pastoral  peoples 
who  live  under  primitive  conditions  the  practice  is  to  promptly 
sour  all  milk  by  permitting  a  vigorous  growth  of  certain  races  of 
lactic  acid-producing  bacteria  in  it.  This  protects  the  milk 
against  proteolytic  organisms  which  produce  unwholesome  de- 
composition products,  because  the  rise  of  acidity  is  so  rapid  that 
all  forms  other  than  the  acid-forming  organisms  and  certain 
yeasts  are  killed  or  their  growth  inhibited.  Sour  milk  is  a  highly 
wholesome  food,  and  is  used  in  enormous  quantities  in  Asia, 
Arabia,  the  Balkan  States,  Northern  Africa  and  in  the  grazing 
sections  of  Abyssinia.  Wherever  it  is  used  in  liberal  amounts 
as  human  food,  the  people  are  of  exceptional  physical  perfection. 
This  will  be  further  discussed  later. 

The  number  of  bacteria  in  milk  depends  upon  the  temperature 
and  age  and  the  amount  of  dirt  which  is  allowed  to  contaminate 
it.  In  America  it  is  the  custom  to  market  liquid  milk  either 
raw  or  pasteurized.  In  order  that  this  may  be  done  in  a  satis- 
factory manner  great  care  must  be  exercised  in  respect  to  clean- 
liness of  cows  and  of  milkers  and  of  utensils;  and  refrigeration 
must  be  immediate  and  effective  and  delivery  prompt.  There 
has  been  steady  progress  in  the  supervision  of  the  milk  supply  of 
cities  in  recent  years  and  American  cities  have  the  most  whole- 
some milk  supplies  in  the  world.  All  city  milk  supplies  should 
be  pasteurized.  This  is  effected  by  heating  the  milk  during 
thirty  minutes  to  a  temperature  of  145  degrees,  followed  by 
prompt  cooling  and  bottling  in  sterile  containers.  This  prevents 
the  spread  of  typhoid  fever,  scarlet  fever,  tuberculosis  and  other 
diseases  which  are  sometimes  milk  borne. 

Bacteria  in  milk  are  related  to  infant  mortality.  Children  fed 
clean  milk  with  few  bacteria  have  a  lower  death  rate  than  those 
who  take  milk  with  high  bacterial  counts.  Many  organisms 
which  are  relatively  harmless  to  adults  may  cause  diarrhea  in 
infants  and  young  children,  or  at  least  set  up  intestinal  in- 
flammation. 

161.  City  Milk  Supply  Should  Be  Rigidly  Inspected.— The 
desirability  of  thorough  control  of  a  city  milk  supply  through 
the  agency  of  the  health  department  has  been  fully  justified  by 
the  results.  Bacterial  counts  should  be  made  regularly  of  market 


152     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

milk,  (1)  as  an  indicator  of  the  care  exercised  in  keeping  healthy 
cows  and  in  exercising  cleanliness  on  the  farm,  refrigeration  and 
promptness  of  delivery;  (2)  as  a  basis  of  condemning  milk  which 
is  unwholesome  because  containing  dirt,  filth,  or  decomposed 
materials.  Dairy  inspection  has  come  to  be  a  well  recognized 
method  of  insuring  a  wholesome  milk  supply. 

162.  Eggs. — Eggs  contain  everything  that  is  necessary  for 
the  growth  and  maintenance  of  the  body,  but  are  particularly 
lacking  in  calcium,  and  are  unbalanced  with  respect  to  certain 
other  food  principles.    Thus,  eggs  are  very  rich  in  fats  and  re- 
lated substances,  and  are  nearly  lacking  in  carbohydrates.     A 
diet  exclusively  of  eggs,  or  in  which  eggs  are  a  prominent  con- 
stituent will  favor  putrefactive  processes  in  the  alimentary  tract. 
For  these  reasons,  eggs  are  to  be  regarded  as  articles  which  should 
be  of  secondary  importance  so  far  as  amount  is  concerned.    They 
have,  however,  most  exceptional  dietary  properties  which  makes 
it  desirable  to  use  them  where  the  item  of  expense  is  not 
prohibitive. 

The  fats  of  eggs  are  fully  comparable  with  butter  fat  as  a 
source  of  the  fat-soluble  A  (42),  and  egg  yolk  is  at  least  com- 
paratively rich  in  water-soluble  B,  and  in  water-soluble  C.  The 
proteins  of  egg  are  believed  to  be  of  high  biological  value.  In 
the  developing  chick  there  is  considerable  absorption  of  lime  from 
the  shell,  and  in  this  way  the  shortage  of  calcium  in  the  organic 
content  of  the  egg  is  made  good.  When  we  eat  eggs,  we  cast  out 
the  shell  and  thus  take  the  part  which  is  deficient  in  lime. 

It  will  be  seen,  therefore,  that  eggs  may  have  an  important 
place  in  enhancing  the  quality  of  a  cereal,  tuber  and  meat  diet, 
but  that  they  cannot  logically  be  considered  a  substitute  for 
milk.  They  should  be  eaten  with  a  diet  rich  in  carbohydrates  to 
discourage  the  tendency  for  putrefaction  in  the  intestine,  which 
they  favor,  and  should  be  used  to  confer  palatability  on  other 
foods  rather  than  as  a  prominent  constituent  of  the  food  supply. 

163.  Sea  Foods. — Foods  of  the  class  to  which  oysters,  crabs 
and  clams  belong,  assume  a  new  importance  in  the  light  of  the 
nutrition  studies  which  have  so  clearly  shown  the  inferiority  of 
muscle  meats  as  compared  with  the  secretory  organs  and  tissues 
which  are  concerned  with  the  transformation  of  foods  to  end- 
products  of  metabolism,  i.  e.,  the  glandular  organs   (52).     In 
clams,  oysters  and  soft  crabs,  we  eat  the  entire  animal  except  its 
exo-skeleton,  the  shell.    This  insures  the  consumption  of  tissues 
containing  all  the  uncharacterized  food  substances,  and  makes 


DIETARY  PROPERTIES  OF  FOODSTUFFS        153 

these  articles  of  diet,  supplementary  foods  in  the  sense  that  they 
are  likely  to  add  to  the  diet  some  principles  which  it  in  many 
instances  contains  in  amounts  below  the  optimum. 

While  such  articles  are  not  necessary  in  a  diet  which  contains 
the  requisite  amount  of  milk  and  the  leafy  vegetables,  and  must 
be  regarded  as  somewhat  expensive  foods  to  be  eaten  as  an  in- 
dulgence of  the  appetite,  the  shellfish  doubtless  played  a  most 
important  role  in  the  nutrition  of  early  man.  Numerous  shell- 
heaps  or  "kitchen  middens"  of  enormous  proportions  occur  on 
the  Atlantic  coast  of  America  and  Europe.  These  were  the  sites 
of  human  habitations  over  long  periods  and  indicate  that  these 
shore  dwellers  depended  in  great  measure  on  shellfish  for  their 
sustenance.  Their  type  of  diet  represented  a  peculiar  kind  of 
carnivorous  feeding  which  was  very  satisfactory. 

BIBLIOGRAPHY 

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nutrients  of  blue-grass,  Ohio  Agr.  Exp.  Sta.  Bull.  222,  1910. 
Forbes,  E.  B.,  Beegle,  F.  M.,  and  Mensching,  J.  E.:    Ibid.,  255,  1913. 

2.  McCollum,  E.  V.,  Simmonds,  N.,  and  Pitz,  W.:     The  nature  of  the 

dietary  deficiencies  of  wheat  embryo,  Jour.  Biol.  Chem.,  1916, 
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Amer.  Jour.  Dis.  of  Child.,  1917,  xiii,  98. 

4.  Hart,  E.  B.,  McCollum,  E.  V.,  Steenbock,  H.,  and  Humphrey,  G.  C.: 

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from  restricted  sources,  Wis.  Agr.  Exp.  Sta.  Bull.  17,  1911. 
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corn  or  wheat  grain,  Jour.  Biol.  Chem.,  1914,  xix,  373. 
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of  the  wheat  kernel  at  different  planes  of  intake,  Jour.  Biol.  Chem., 

1916,  xxviii,  211. 

5.  Osborne,  T.  B.,  and  Mendel,  L.  B.:    The  nutritive  value  of  the  pro- 

teins of  the  wheat  kernel  and  its  milling  products,  Jour.  Biol.  Chem., 
1919,  xxxvii,  557. 

6.  Chick,  H.,  and  Hume,  E.  M.:   The  distribution  in  white  rice  and  maize 

grains  of  the  substance,  the  deficiency  of  which  in  the  diet  causes 
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B,  1917,  xc,  44. 

7.  Chick,   and   Hume:     The  distribution  among   food-stuffs    (especially 

those  suitable  for  the  rationing  of  armies)  of  the  substances  required 
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Army.  Med.  Corps,  August  1917. 

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9.  Chick,  H.,  and  Delf,  E.  M.:    The  anti-scorbutic  value  of  dry  and 

degerminated  seeds,  Biochem.  Jour.,  1919,  xiii,  199. 

10.  Steenbock,  H.,  and  Boutwell,  P.  W.:     The  comparative  nutritive  value 
of  white  and  yellow  maizes,  Jour.  Biol.  Chem.,  1920,  xli,  81. 


154     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

11.  McCollum,  E.  V.,  and  Da^is,  M.:     The  nature  of  the  dietary  defi- 

ciencies of  rice,  Jour.  Biol.  Chem.,  1915,  xxiii,  181. 

12.  Steenbock,  H.,  Kent,  H.,  and  Gross,  E.  G.:     The  dietary  qualities  of 

barley,  Jour.  Biol.  Chem.,  1918,  xxxv,  61. 

Osborne,  and  Mendel:  Nutritive  value  of  the  proteins  of  barley,  oat, 
rye,  and  wheat  kernel,  Jour.  Biol.  Chem.,  1919,  xli,  275. 

13.  McCollum,   Simmonds,   and   Pitz:      The    dietary   deficiencies   of   the 

white  bean,  Jour.  Biol.  Chem.,  1917,  xxix,  521. 

McCollum,  Simmonds,  and  Parsons:  The  dietary  properties  of  the 
pea  (Vicia  sativa),  Jour.  Biol.  Chem.,  1919,  xxxvii,  287. 

14.  Osborne,    and    Mendel:      Beobachtungen    uber    Wachstum    bei    Fiit- 

terungsversuchen  mit  isolierten  Nahrungssubstanzen,  Zeit.  f.  physiol. 
Chem.,  1912,  Ixxx,  307. 

15.  Daniels,  A.  L.,  and  Nichols,  N.  B.:     The  nutritive  value  of  the  soy 

bean,  Jour.  Biol.  Chem.,  1917,  xxxii,  91. 

Osborne,  and  Mendel:  The  use  of  soy  beans  as  food,  Jour.  Biol. 
Chem.,  1917,  xxxii,  369. 

16.  Daniels,  A.  L.,  and  Loughlin,  R.:     Feeding  experiments  with  peanuts, 

Jour.  Biol.  Chem.,  1918,  xxxiii,  295. 

17.  Johns,  C.  0.,  and  Jones,  D.  B.:     The  proteins  of  the  peanut,  Jour. 

Biol.  Chem.,  1917,  xxx,  33. 

18.  Richardson,  A.  E.,  and  Green,  H.  S.:     Nutrition  investigations  upon 

cottonseed  meal,  Jour.  Biol.  Chem.,  1916,  xxv,  307;  1917,  xxx,  243. 

19.  Osborne,  and  Mendel:     The  use  of  cottonseed  as  food,  Jour.  Biol. 

Chem.,  1917,  xxix,  289. 

Wells,  C.  A.,  and  Ewing,  P.  V.:     Cottonseed  meal  as  an  incomplete 
food,  Jour.  Biol.  Chem.,  1916,  xxvii,  15. 

20.  Osborne,  and  Mendel:     The  relative   value  of  certain  proteins  and 

protein   concentrates   as   supplements   to   corn   gluten,   Jour.   Biol. 
Chem.,  1917,  xxxix,  69. 

21.  Withers,  W.  A.,  and  Carruth,  F.  E.:     Gossypol,  the  toxic  substance 

in  cottonseed  meal,  Jour.  Agric.  Res.,  1915,  v,  261. 

22.  Carruth,  F.  E.:     Methods  of  approximating  the  toxicity  of  cottonseed 

products,  Jour.  Biol.  Chem.,  1917,  xxxii,  87. 

23.  McCollum,  Simmonds,  and  Pitz:     The  vegetarian  diet  in  the  light  of 

our   present   knowledge    of   nutrition,   Amer.   Jour.   Physiol.,    1916, 
xli,  333. 

McCollum,  Simmonds,  and  Pitz:  The  supplementary  dietary  relation- 
ship between  leaf  and  seed  as  contrasted  with  combinations  of  seed 
with  seed,  Jour.  Biol.  Chem.,  1917,  xxx,  13. 

24.  Osborne,  and   Mendel:     The  vitamines  in  green  foods,  Jour.   Biol. 

Chem.,  1919,  xxxvii,  187. 

The  proteins  of  green  leaves — spinach  leaves,  Ibid.,  1920,  xlii,  1. 

The  fat-soluble  vitamine,  Ibid.,  1920,  xli,  549. 

25.  Steenbock,  and  Gross :    The  fat-soluble  vitamine  content  of  green  plant 

tissues  together  with  some  observations  on  their  water-soluble  vita- 
mine  content,  Jour.  Biol.  Chem.,  1920,  xli,  149. 

26.  McCollum,  Simmonds,  and  Parsons:     The  dietary  properties  of  the 

potato,  Jour.  Biol.  Chem.,  1918,  xxxvi,  197. 

27.  Rose,   M.  S.,  and  Cooper,  L.  F.:     The  biological   efficiency   of  the 

potato  nitrogen,  Jour.  Biol.  Chem.,  1917,  xxx,  201. 
Hindhede,  M.:    Eine  Reform  unserer  Ernahrung.  Kopenhagen,  1908; 


DIETARY  PROPERTIES  OF  FOODSTUFFS        155 

Also  The  effect  of  food  restriction  during  the  war  on  mortality  in 
Copenhagen,  Jour.  Amer.  Med.  Assoc.,  1920,  Ixxiv,  381.  Modern 
Ernahrung,  Berlin,  W.  Vobach,  1915. 

28.  Steenbock,   and   Gross:     The   fat-soluble   vitamine   content   of   roots 

together  with  some  observations  on  their  water-soluble  vitamine 
content,  Jour.  Biol.  Chem.,  1919,  xl,  501. 

29.  Denton,  M.  C.,  and  Kohman,  E.  A.:     Feeding  experiments  with  raw 

and  boiled  carrots,  Jour.  Biol.  Chem.,  1918,  xxxvi,  249. 
Kohman,  E.  A.:     Experimental  production  of  edema  as  related  to 
"war  dropsy,"  Amer.  Jour,  of  Physiol.,  1920,  li,  378. 

30.  Osborne,  and  Mendel:     The  occurrence  of  the  water-soluble  vitamine 

in  some  common  fruits,  Jour.  Biol  Chem.,  1920,  xlii,  465. 
Daniels,  A.  L.,  Byfield,  A.  H.,  and  Loughlin,  R.:    The  anti-neuritic 
and  growth  stimulating  properties  of  orange  juice,  Amer.  Jour.  Dis. 
Child.,  1920,  xix,  349. 

31.  McCollum,  and  Simmonds:   Unpublished  data. 

32.  Sugiura,  K.,  and  Benedict,  S.  R.:    The  nutritive  value  of  the  banana, 

Jour.  Biol.  Chem.,  1918,  xxxvi,  171 ;  Ibid.,  1919,  xl,  449. 

33.  Loeb,  J.,  and  Northrup,  J.  H.:     Influence  of  food  and  temperature 

upon  the  duration  of  life,  Jour.  Biol.  Chem.,  1917,  xxxii,  103. 
Northrup,  J.  H.:    The  effect  of  prolongation  of  the  growth  period  on 
the  total  duration  of  life,  Jour.  Biol.  Chem.,  1917,  xxxii,  123. 

34.  Cajori,  F.  A.:    Some  nutritive  properties  of  nuts:    Their  proteins  and 

content  of  water-soluble  vitamine,  Jour.  Biol.  Chem.,  1920,  xliii,  583. 
Haliburton,  W.  D.,  and  Drummond,  J.  C.:     The  nutritive  value  of 

margarines  and  butter  substitutes,  Jour,  of  Physiol.,  1917,  li,  235. 
Coward,  K.  H.,  and  Drummond,  J.  C.:    Nuts  as  a  source  of  vitamine 

A,  Biochem.  Jour.,  1920,  xiv,  665. 

35.  Watson,  C.:     The  effects  of  protein  feeding,  Med.  Chirurg.  Trans., 

1904,  liii,  87. 

The  influence  of  a  meat  diet  on  the  thyroid  gland  in  the  second 

generation  of  rats,  Jour.  Physiol.,  1906,  xxiv,  p.  xxix  (proceedings). 

36.  Watson,  C.,  and  Hunter,  A.:     Observations  on  diet.    The  influence  of 

diet  on  growth  and  nutrition,  Jour,  of  Physiol.,  1906,  xxxiv,  p.  iii. 

37.  Osborne,  and  Mendel:     Nutritive  factors  in  animal  tissues,  Jour.  Biol. 

Chem.,  1917,  xxxii,  309;  Ibid.,  1918,  xxxiv,  17. 

38.  McCollum,  and  Davis:  Nutrition  with  purified  food  substances,  Jour. 

Biol.  Chem.,  1915,  xx,  641. 

The   influence    of   certain  vegetable   fats   on   growth,   Ibid.,   1915; 

xxi,  179. 

39.  Parsons,  H.  T.:    The  anti-scorbutic  content  of  certain  body  tissues  of 

the  rat,  Jour.  Biol.  Chem.,  1920,  xliv,  587. 

40.  Cooper,  E.  A.:     On  the  protective  and  curative  properties  of  certain 

food-stuffs  against  polyneuritis  induced  in  birds  by  a  diet  of  polished 
rice,  Jour.  Hygiene,  1912,  xii,  436. 

The  preparation  from  animal  tissues  of  a  substance  which  cures 
polyneuritis  induced  in  birds  by  a  diet  of  polished  rice,  Biochem. 
Jour.,  1913,  vii,  268. 

41.  McCollum,  Simmonds,  and  Parsons:     The  supplementary  dietary  rela- 

tions between  animal  tissues  and  legume  seeds,  Jour.  Biol.  Chem., 
1921,  xlvii,  139. 


156     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

42.  McCollum,  and  Davis:     The  necessity  of  certain  lipins  in  the  diet 

during  growth,  Jour.  Biol.  Chem.,  1913,  xv,  167. 

43.  Osborne,  and  Mendel:     The  effect  of  butter  fat  on  growth,  Jour.  Biol. 

Chem.,  1913-14,  xvi,  423. 

44.  Osborne,    and    Mendel:      Further    observations    on   the    influence    of 

natural  fats  upon  growth,  Jour.  Biol.  Chem.,  1915,  xx,  379. 

45.  Halliburton,  W.  D.,  and  Drummond,  J.  C.:     The  nutritive  value  of 

margarines  and  butter  substitutes  with  reference  to  their  content 
of  the  fat-soluble  accessory  substance,  Jour.  Physiol.,  1917,  li,  235. 

46.  Daniels,  and  Loughlin:     Note  on  the  fat-soluble  growth  promoting 

substance  in  lard  and  cottonseed  oil,  Jour.  Biol.  Chem.,  1920,  xlii, 
359. 

Drummond,  J.  C.,  Golding,  J.,  and  Coward,  K.  H.:     The  nutritive 
value  of  lard,  Biochem.  Jour.,  1920,  xiv,  742. 

47.  McCollum,    Simmonds,    and    Parsons:      The    nutritive    properties    of 

animal  tissues,  Jour.  Biol.  Chem.,  1921,  xlvii,  111. 

48.  McCollum,  Simmonds,  and  Parsons:     Supplementary  relations  of  the 

proteins   of  milk  for  those   of  cereals,  and   of  milk  for  those  of 
legume  seeds,  Jour.  Biol.  Chem.,  1921,  xlvii,  235. 
Lane-Claypon,  J.  E.:    Milk  and  its  hygienic  relations,   New  York, 
1916. 

49.  Osborne,  and  Mendel:     Milk  as  a  source  of  water-soluble  vitamine, 

Jour.  Biol.  Chem.,  1918,  xxxiv,  537. 

50.  McCollum:     What  to  teach  the  public  regarding  food  values,  Jour. 

Home  Econ.,  1918,  x,  195. 

51.  McCollum,  Simmonds,  and  Parsons:     Supplementary  protein  values  in 

foods,  Jour.  Biol.  Chem.,  1921,  xlvii,  111. 

52.  Drummond,   J.   C.:     The   nutritive   value   of   certain   fish,   Jour,   of 

Physiol.,  1918-19,  lii,  95. 


CHAPTER  VII 
THE  VEGETARIAN  DIET    - 

164.  Vegetarianism  Generally  Practised  as  a  Dietary  Fad. 

— There  has  always  been  a  tendency  for  dietetic  theorists  to  ad- 
vocate the  adoption  of  a  fleshless  diet.  The  proponents  of  this 
system  have  broken  up  into  schools,  the  adherents  of  which  dif- 
fer in  the  fervor  with  which  they  espouse  their  cause.  The  most 
extreme  of  these  are  the  enthusiasts  of  the  fruit  and  nut  diet  (1), 
who  experience  esthetic  pleasure  in  the  thought  that  their  foods 
grow  and  ripen  away  from  contact  with  the  soil  and  suggest, 
therefore,  the  purity  and  fragrance  of  orchard  and  forest,  the 
poetic  joy  of  summer  and  the  inspiration  of  the  rural  landscape. 
Another  group  adopts  the  vegetarian  diet  because  of  an  abhor- 
rence of  the  idea  of  taking  animal  life  for  the  sake  of  food.  These 
two  classes  of  vegetarians  regard  flesh  as  unwholesome  as  well 
as  unethical,  and  defend  with  a  number  of  arguments  the  view 
that  meat  eating  tends  to  moral  debasement  and  physical  de- 
generation. The  third  group,  the  lacto-ovo-vegetarians,  who  per- 
mit the  use  of  milk  and  eggs  along  with  a  diet  otherwise  vege- 
tarian, is  in  general  less  extreme  in  its  ardor  for  ethical  consid- 
erations, and  adheres  to  its  tenets  because  of  conviction  that  it 
makes  for  physical  efficiency  in  a  greater  degree  than  does  meat 
eating. 

165.  Food  Faddists  Frequently  Discredit  Themselves  by 
Their  Philosophy. — While  some  of  the   arguments   offered   in 
sober  earnestness  in  support  of  abstinence  from  flesh  foods  are 
suggestive  of  mental  invalidism,  others  demand  serious  consid- 
eration and  an  answer  based  upon  scientific  understanding.    In 
the  former  category  we  may  place  the  assertion  that  the  anthro- 
poid apes,  regarded  as  cognates  of  our  ancestors,  live  on  fruits, 
nuts  and  cereals,  and  that  this  fact  proves  that  such  a  diet  is  espe- 
cially suited  to  the  nutrition  of  man.    One  may  well  argue  that 
if  a  change  to  meat  eating  in  the  era  of  the  cave  man  has  caused 
or  permitted  him  to  develop  mentally  and  physically  into  what 
the  human  race  is  to-day,  this  change  in  dietary  habits  may  have 

157 


158     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

been  indeed  a  great  piece  of  good  fortune.  The  low  development 
of  other  omnivorous  types  of  animals  weakens  the  force  of  this 
argument.  We  may  also  retort  that  it  is  no  more  advisable  to 
permit  the  apes  to  be  our  guides  in  dietetics  than  in  certain  other 
ways  of  living.  It  is,  however,  well  known  that  the  apes  eat 
insects,  worms,  eggs,  small  birds  and  such  other  animals  as  they 
are  able  to  capture,  and  that  they  also  eat  the  leaves  of  certain 
plants. 

There  is  little  comfort  for  the  vegetarian  enthusiast  in  the 
comparison  of  the  anatomical  structure  of  the  alimentary  tract 
of  man  with  that  of  animals  whose  diets  are  of  different  types. 
The  dentition,  the  size  and  shape  of  the  stomach,  intestine  and 
cecum  of  man  clearly  indicate  suitability  for  a  mixed  diet.  To 
the  esthetic  argument  the  meat  eater  may  reply  that  he  includes 
sufficient  fruits,  nuts  and  cereals  in  his  diet  to  permit  him  to  be 
inspired  by  the  beauties  of  Nature.  To  the  statement  that  a 
refined  person  cannot  eat  meat  until  it  is  cooked,  and  its  flavor 
changed  so  as  to  disguise  its  origin,  the  reply  may  well  be  made 
that  many  fruits  and  vegetables  are  not  at  all  appetizing  until 
cooked  and  so  flavored  as  to  increase  their  palatability.  The 
argument  which  was  at  one  time  considered  to  be  irrefutable  and 
to  be  of  sufficient  force  to  condemn  meat  eating  rested  on  the 
content  of  uric  acid  forming  substances  (purins)  in  flesh  foods. 
Chemical  studies  have,  however,  shown  that  there  are  very 
nearly  comparable  amounts  of  purins  in  many  vegetable  foods, 
such  as  lentils,  oatmeal,  beans,  asparagus,  and  notably  in  tea 
and  in  coffee. 

1 66.  Meat  Eating  Cannot  Be  Condemned  as  Deadening  the 
Moral  Faculties. — A  stock  argument  of  radical  vegetarians  is 
that  meat  eating  deadens  the  moral  and  intellectual  faculties. 
One  who  reflects  that  Moses,  David,  Solomon  and  Jesus  ate  flesh 
foods  cannot  be  deeply  impressed  by  it.    Likewise  the  statement 
that  animals  living  on  a  vegetarian  diet  are  strong  and  tractable, 
while  carnivorous  animals  are  ferocious  does  not  withstand  in- 
quiry.   The  average  bull  or  belligerent  billy  goat  can  strike  terror 
into  the  heart  of  man  with  less  provocation  than  is  necessary  to 
render  dangerous  a  lion  or  a  wolf.    The  gentle  and  happy  dispo- 
sition of  the  Eskimo  on  his  strictly  carnivorous  diet  stands  in 
marked  contrast  to  the  ferocity  with  which  the  vegetarian  Ben- 
galese  deported  themselves  during  the  mutiny  of  1857. 

167.  A  More  Valid  Argument  Against  Meat  Eating. — The 
more  valid  arguments  concerning  the  use  of  meat  as  contrasted 


THE  VEGETARIAN  DIET  159 

with  the  fleshless  dietary  regimen,  are  based  upon  the  view  that 
meat  is  unwholesome  and  that  it  contains  waste  products,  which, 
because  of  their  poisonous  properties,  tend  to  do  damage  to  the 
body  tissues.  This  view  is  upheld  by  experimental  results.  Pro- 
fessor Irving  Fisher  of  Yale  conducted  extensive  experiments 
with  flesh  abstainers  and  flesh  eaters,  and  found  the  former  pos- 
sessed of  much  greater  endurance  than  the  latter.  The  tests  in- 
volved holding  the  arms  outstretched,  knee  bending,  and  exer- 
cises of  similar  nature.  The  flesh  abstainers  were  three  to  six 
times  as  capable  of  endurance  as  were  the  flesh  eaters  (2).  Simi- 
lar results  have  been  reported  by  Kellogg  (3). 

It  would  be  unprofitable  to  review  further  the  old  debate  con- 
cerning the  relative  merits  of  meat  eating  and  meat  abstinence. 
There  was  no  evidence  of  a  conclusive  nature  upon  which  the 
question  could  be  decided.  Those  who  were  not  convinced  by 
the  results  of  Fisher's  endurance  tests  and  those  of  others  could 
argue  that  the  vegetarians  were  enthusiastic  exponents  of  a  fad 
in  order  to  defend  which  they  exerted  themselves  to  the  utmost, 
whereas  the  meat  eaters  were  not  so  determined  to  justify  a  prac- 
tice which  is  all  but  universal,  and  which  seems  to  them  satis- 
factory. Hence  they  did  not  have  the  same  psychological  atti- 
tude toward  the  contest  as  did  their  antagonists.  There  were 
factors  not  then  appreciated,  which  are  of  vital  importance  in 
the  discussion  of  the  vegetarian  diet.  These  can  best  be  made 
clear  by  describing  certain  experimental  work  which  has  a  direct 
bearing  on  the  subject. 

1 68.  Slonaker's  Study  of  the  Vegetarian  Diet. — The  most 
elaborate  attempt  to  test  the  relative  merits  of  the  strictly  vege- 
tarian diet  as  contrasted  with  the  omnivorous  type  was  made  by 
Slonaker  (4).  He  fed  a  group  of  young  rats  on  a  list  of  23  vege- 
table foods,  allowing  them  free  choice  within  limits.  For  com- 
parison a  similar  group  were  fed  the  same  foods  of  vegetable 
origin,  but  in  addition  animal  food  was  given  in  moderate  quan- 
tities. Since  several  natural  foods,  raw  or  prepared,  were  offered 
at  a  time,  and  the  animals  were  allowed  free  choice  as  to  what 
they  should  eat,  and  since  no  effort  was  made  to  keep  a  record 
of  food  consumption  or  of  the  relative  amounts  of  the  different 
foods  eaten,  the  results  cannot  be  used  for  critical  examination 
except  in  a  limited  way.  They  are,  however,  of  the  utmost  in- 
terest in  showing  how  far  instinct  fails  to  guide  an  animal  in  the 
selection  of  food.  Slonaker's  list  of  foods  included  nearly  every- 
thing which  a  vegetarian  in  Southern  California  would  be  likely 


160     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

to  have  on  his  table  and  included  seeds,  the  milling  products  of 
seeds,  leafy  vegetables,  tubers  and  fleshy  roots. 

The  vegetarian  group  grew  fairly  well  for  a  time,  but  became 
stunted  when  they  reached  a  weight  of  about  60  per  cent  of  the 
normal  adult  size.  They  never  increased  in  weight  beyond  this 
point.  The  omnivorous  controls  grew  steadily  to  what  may  be 
regarded  as  the  normal  size  for  the  adult.  The  vegetarians  lived, 
on  the  average  for  the  entire  group,  555  days,  whereas  the  om- 
nivora  had  an  average  span  of  life  of  1,020  days.  The  vegetarian 
rats,  in  other  words,  grew  to  be  about  half  as  large  and  lived  half 
as  long  as  did  their  fellows  receiving  animal  food.  Slonaker 
drew  the  conclusion  that  a  strictly  vegetarian  diet  was  not  suit- 
able for  the  nourishment  of  an  omnivorous  animal,  but  was  not 
able  to  give  the  cause  of  the  deficiency. 

169.  Even  with  Wide  Variety  Vegetarianism  Is  Likely  to 
Lead  to  Disaster. — The  results  of  Slonaker's  experiments  were 
published  in  1912,  and  just  at  the  time  when  McCollum  and 
Davis  were  securing  the  experimental  data  which  revealed  the 
differences  in  the  growth-promoting  power  of  fats  from  different 
sources,  and  which  established  the  existence  of  a  new  and  hith- 
erto unsuspected  dietary  essential.  They  fed  rats  on  relatively 
pure  food-stuffs  as  described  in  Chapter  II  with  various  fats  of 
both  animal  and  vegetable  origin,  and  found  that  no  fat  which 
was  derived  from  plant  tissues  could  compare  in  growth-pro- 
moting properties  with  butter  fat,  egg  yolk  fats  and  the  fats 
from  the  glandular  organs.  It  seemed  to  them  that  the  most 
probable  explanation  of  the  results  of  Slonaker  was  the  absence 
or  shortage  in  his  vegetarian  diet  of  the  dietary  essential  fur- 
nished so  abundantly  by  these  animal  fats,  and  which  later  came 
to  be  designated  as  fat-soluble  A.  A  low  protein  intake  was 
possibly  another  cause  for  Slonaker's  failure.  With  this  idea  in 
mind  they  tried  during  the  summer  of  1914,  an  experiment  simi- 
lar to  that  of  Slonaker,  but  so  modified  as  to  give  the  animals  a 
much  higher  protein  intake  than  his  animals  probably  enjoyed. 
It  seemed  that  if  Slonaker's  rats  ate  liberally  of  such  leaves  as 
cabbage  and  other  leafy  vegetables  and  of  tubers  and  roots  the 
protein  content  of  which  in  the  fresh  condition  does  not  as  a 
rule  exceed  2  per  cent,  the  protein  in  the  other  components  of 
the  diet  might  not  have  been  high  enough  to  give  the  entire  ra- 
tion consumed  a  content  in  their  food  sufficiently  high  to  pro- 
mote growth  at  the  optimum  rate. 

McCollum  and  Davis,  therefore,  fed  their  rats  a  diet  which 


THE  VEGETARIAN  DIET  161 

afforded  a  choice  among  the  following  list  of  foods :  wheat,  maize, 
rye,  oat  (rolled),  wheat  germ,  maize  gluten,  wheat  gluten,  flax- 
seed  oil  meal,  green  clover,  green  alfalfa  leaves,  onions,  peanuts, 
and  cooked  navy  beans  and  peas.  With  the  exception  of  the  last 
two  articles  the  foods  were  fed  raw.  It  will  be  observed  that  in 
this  list  there  are  several  vegetable  foods  having  unusually  high 
protein  contents.  Maize  gluten,  a  by-product  of  starch  manu- 
facture, contains  about  25  per  cent;  wheat  gluten,  prepared  by 
washing  ground  wheat  free  from  starch,  about  85  per  cent;  flax- 
seed  oil  meal,  30  per  cent  and  wheat  germ  30-35  per  cent.  Since 
animals  are  known  to  grow  well  on  many  diets  containing  15  to 
18  per  cent,  of  protein,  it  seemed  that  with  this  variety  to  select 
from  one  possible  cause  of  failure  in  Slonaker's  experiments,  too 
low  a  protein  intake,  would  be  avoided.  McCollum  and  Davis 
had  at  that  time  not  discovered  that  the  leaf  of  the  plant  is  a 
moderately  good  source  of  the  dietary  essential  fat-soluble  A, 
although  it  was  known  that  the  leafy  foods  enable  herbivorous 
animals  to  thrive  on  diets  derived  entirely  from  plant  sources. 
It  was  then  assumed  that  when  both  the  leaves  and  so  many  dif- 
ferent kinds  of  seeds  and  seed  products  were  supplied,  there  could 
be  little  doubt  that  everything  a  herbivorous  animal  requires  was 
present  in  the  foods. 

The  rats  fed  this  wide  variety  of  vegetable  foods,  and  supplied 
with  liberal  amounts  of  protein,  duplicated  in  all  respects  the 
results  described  by  Slonaker.  They  grew  at  about  half  the  nor- 
mal rate  for  the  first  few  weeks,  then  became  permanently 
stunted,  none  ever  reaching  a  size  much  greater  than  half  that 
of  the  average  normal  adult.  The  addition  of  butter  fat  to  the 
diet  of  some  of  these  animals  failed  to  benefit  them  in  any  notice- 
able degree.  The  answer  to  the  question  as  to  why  rats  did  not 
thrive  on  such  strictly  vegetarian  food  mixtures  was  not  secured 
from  these  experiments.  It  was,  however,  soon  after  learned 
wherein  lay  the  cause  of  failure. 

170.  Rats  Can  Be  Grown  Successfully  on  a  Strictly  Vege- 
tarian Diet. — McCollum,  Simmonds  and  Pitz  fed  a  group  of 
young  rats  on  a  monotonous  diet  consisting  of  maize  kernel  50, 
alfalfa  leaf  (dry)  30,  and  cooked  (dry)  peas,  subsequently  dried, 
20  per  cent.  The  three  ingredients  were  ground  together  so  that 
whatever  was  eaten  represented  the  formula  for  the  diet.  The 
diet  induced  growth  at  approximately  the  normal  rate,  and  re- 
production and  rearing  of  a  considerable  number  of  young.  The 
young  grew  up  to  the  full  adult  size  and  were  successful  in  rear- 


162      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

ing  a  considerable  number  of  their  offspring  (see  Chart  7). 
Without  ever  tasting,  after  the  weaning  period,  anything  other 
than  this  monotonous  mixture  as  their  sole  source  of  nutriment 
this  family  of  rats  remained  approximately  normal  in  vigor  and 
successfully  weaned  the  young  of  the  fourth  generation  with  no 
apparent  diminution  in  vitality.  At  this  point  the  experiment 
was  discontinued  (5). 

McCollum,  Simmonds  and  Pitz  next  carried  out  another  series 
of  feeding  experiments  with  rats,  the  diets  of  which  were  derived 
solely  from  a  mixture  of  a  leaf  and  a  seed  ground  together  so 
that  the  two  parts  of  the  ration  could  not  be  picked  out  and 
separately  eaten  (6).  In  marked  contrast  to  the  failure  of  ani- 
mals to  grow  on  any  mixture  of  seeds,  it  was  found  that  in  many 
cases  a  mixture  of  a  seed  and  a  leaf  formed  a  diet  on  which  con- 
siderable growth  could  be  secured.  Even  polished  rice,  which, 
as  has  already  been  described,  requires  supplementing  with  re- 
spect to  four  dietary  factors,  mineral  salts,  fat-soluble  A,  water- 
soluble  B  and  protein,  before  it  becomes  complete  for  the  rat,  was 
found  to  induce  fairly  good  growth  when  fed  with  ground  alfalfa 
leaves  in  the  proportion  of  60  per  cent  of  seed  to  40  per  cent  of 
leaf.  On  this  simple  and  monotonous  mixture  young  rats  grew 
from  weaning  time  to  83  per  cent  of  the  normal  adult  size.  One 
female  even  produced  two  litters  of  young,  but  allowed  them 
to  die  within  a  few  days.  A  mixture  of  rolled  oats  60  per  cent 
and  alfalfa  leaves  40  per  cent  ground  together  makes  a  much 
better  ration.  On  this  simple  mixture  young  rats  have  been 
observed  to  grow  to  the  full  adult  size  and  to  reproduce  and  rear 
young.  One  female  reared  fourteen  out  of  seventeen  young  born 
in  three  litters.  Maize  and  alfalfa  leaf  or  wheat  and  alfalfa 
leaf  were  not  so  satisfactory  for  the  promotion  of  growth  as  is 
the  corresponding  mixture  containing  rolled  oats.  Mixtures  of 
the  alfalfa  leaf  with  the  legume  seeds,  peas  and  beans  gave  still 
poorer  results.  The  peas  and  beans  were  always  cooked  and 
subsequently  dried  before  feeding. 

These  experiences  made  it  evident  that  there  is  nothing  in 
vegetarianism  per  se}  which  makes  it  impossible  for  an  animal  of 
the  omnivorous  type  to  be  satisfactorily  nourished  on  this  kind 
of  diet.  It  is  only  necessary  to  make  the  proper  selection  of 
food-stuffs,  and  to  combine  them  in  the  right  proportions.  In 
all  the  experiments  described,  in  which  the  diet  was  made  up  of 
so  simple  a  mixture  as  one  leaf  and  one  seed,  optimum  growth, 
reproduction  and  rearing  of  young  were  in  no  case  secured. 


163 


I 


164      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

171.  The  Cause  of  Failure  of  Slonaker's  Vegetarian  Rats. 
— The  failure  of  Slonaker's  rats  to  thrive  on  the  vegetarian  diet 
is  to  be  explained  on  the  basis  of  several  faults.  In  the  first 
place,  the  diet  was  of  such  a  nature  that  the  animals  could  hardly 
do  otherwise  than  take  a  rather  low  protein  intake.  Secondly, 
the  leaves,  which  formed  the  only  components  of  the  food  supply 
containing  enough  mineral  elements  to  support  growth,  were  fed 
in  the  fresh  condition.  In  this  form  the  water  content  and  bulk 
are  so  great  that  it  would  be  practically  impossible  for  an  animal 
whose  digestive  apparatus  is  no  more  capacious  than  that  of  an 
omnivorous  rat  to  eat  a  sufficient  amount  of  leaf  to  correct  the 
inorganic  deficiencies  of  the  rest  of  the  mixture,  which  consisted 
of  grains,  seeds,  tubers,  and  root  foods.  The  same  physical 
limitations  would  likewise  determine  the  failure  of  the  animals 
to  secure  enough  of  the  fat-soluble  A  to  supplement  the  deficiency 
of  all  the  ingredients  of  their  diet  other  than  the  leaves.  This 
would  not  form  so  important  a  fault  as  the  inorganic  deficiencies 
but  would  be  an  important  depressing  factor.  Success  or  failure 
would  also  turn  in  great  measure  upon  the  extent  to  which  the 
animals  would  be  guided  by  instinct  in  the  selection  of  the  pro- 
portions of  the  several  types  of  food-stuffs  offered  them.  In  the 
opinion  of  McCollum  the  appetite  is  by  no  means  so  safe  a  guide 
for  the  proper  selection  of  foods  as  has  generally  been  supposed. 

From  the  results  of  the  experiments  just  described  it  was  neces- 
sary to  conclude  that  the  leaf  differs  from  the  seed  in  the  respect 
that  it  contains  in  satisfactory  amounts  the  dietary  factors  found 
in  the  latter  in  too  small  amounts.  (Compare  Charts  7  and  8.) 
These  include  the  three  inorganic  elements,  calcium,  sodium  and 
chlorin,  fat-soluble  A  and  proteins  which  supplement  at  least 
in  some  degree  those  of  the  seed.  These,  it  will  be  remembered, 
are  the  three  and  only  purified  food  factors  which  need  be  added 
to  each  of  the  seeds  in  order  to  make  for  dietetic  completeness. 
It  is,  therefore,  possible  to  devise  a  diet  derived  entirely  from 
vegetable  materials,  which  will  produce  normal  growth  and 
optimum  physiological  well-being. 

A  point  of  special  interest  which  it  is  well  to  emphasize,  is  that 
the  bones  of  these  vegetarian  rats  were  of  very  good  quality. 
There  was  no  evidence  in  any  of  the  young  of  the  occurrence  of 
rickets,  a  disease  which  invariably  shows  a  tendency  to  develop 
in  young  animals  restricted  to  a  diet  of  cereal  grains.  The  exact 
nature  of  the  defects  in  the  diet  which  causes  this  disease  of  the 
skeleton  cannot  be  profitably  entered  into  here,  but  will  be  con- 


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165 


166     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

sidered  in  a  separate  chapter.  It  must  suffice  to  say  that  a  satis- 
factory adjustment  among  the  mineral  constituents  in  the  food, 
and  the  presence  of  an  organic  factor  which  exerts  an  important 
influence  on  bone  formation,  are  indispensable  conditions  of  nor- 
mal skeletal  development.  These  conditions  are  not  fulfilled  by 
any  diet  composed  of  cereal  grains  and  other  seeds.  The  results 
of  this  experiment  demonstrate,  therefore,  that  the  mineral  con- 
tent of  the  leaf  component  of  the  vegetarian  diet  employed,  sup- 
plemented the  unsatisfactory  inorganic  nutrients  of  the  seed 
portion,  so  as  to  favor  normal  bone  development.  It  is  also  evi- 
dent that  this  diet  contained  sufficient  of  the  organic  factor  con- 
cerned with  the  metabolism  of  the  osteoblast,  since  no  skeletal 
defects  were  observed.  It  should  also  be  emphasized  that  in 
China  and  other  parts  of  the  Orient  where  green,  leafy  vegetables 
constitute  a  very  important  part  of  the  food  supply,  rickets  is 
almost  unknown  as  a  disease  of  children,  whereas  it  is  common 
in  Europe  and  America,  where  the  tendency  in  numerous  homes 
is  to  derive  a  large  part  of  the  food  supply  from  milled  cereals, 
meat,  legume  seeds  and  tubers. 

172.  Eward's  Studies  on  the  Appetite  as  a  Guide  to  the 
Selection  of  Food. — At  the  Iowa  Experiment  Station,  Evvard 
has  conducted  extensive  experiments  of  a  character  which  were 
intended  to  demonstrate  that  the  appetite  and  instincts  of  the 
hog  serve  to  enable  it  to  make  such  an  adjustment  of  the  relative 
amounts  of  the  several  food-stuffs  offered  it,  as  may  induce  better 
results  in  the  rate  of  growth  than  can  be  generally  secured  when 
the  adjustment  is  made  by  the  feeder,  and  when  the  mixture  of 
the  ingredients  of  the  ration  are  offered  in  a  form  admitting  of 
no  choice  by  the  animal  (7).  The  data  secured  seem  to  show 
that  there  is  some  basis  for  the  belief  that  this  element  of  selec- 
tion by  the  animal  itself  is  worth  taking  advantage  of.  It  should 
be  mentioned  that  as  a  rule  in  all  these  trials  the  animals  were 
given  a  choice  of  only  three  foods,  one  of  these  being  a  cereal 
grain,  another,  a  protein-rich  food,  and  a  third  a  plant  leaf.  In 
some  experiments  a  salt  mixture  was  made  available.  The  rea- 
sons for  the  employment  of  the  leaf  as  a  never-failing  component 
of  the  food  supply  of  the  growing  pig  could  not  have  been  ex- 
plained before  the  studies  of  McCollum  and  his  associates  with 
simplified  diets  and  with  diets  restricted  to  a  single  food-stuff. 
Feeding  such  diets  with  single  and  multiple  food  additions  led  to 
a  knowledge  of  the  exact  nature  of  the  dietary  faults  of  each. 
In  .connection  with  the  types  of  diets  employed  by  Evvard  it 


THE  VEGETARIAN  DIET  167 

should  be  mentioned  that  in  case  the  animal  ate  fairly  liberally 
of  all  the  food-stuffs  offered  it,  a  serious  mistake  would  be  hardly 
made,  since  the  proportions  of  the  several  components  eaten  could 
be  varied  to  a  considerable  degree  without  preventing  growth. 
In  the  case  of  the  mixture  of  maize,  50  per  cent,  alfalfa  leaves, 
30  per  cent,  and  peas,  20  per  cent,  described  above  (Chart  7), 
it  has  been  found  that  for  the  rat  these  are  the  best  proportions 
in  which  these  three  ingredients  can  be  mixed  for  the  promotion 
of  growth  and  reproductive  processes.  It  has  been  further  estab- 
lished that  with  the  use  of  these  three  food-stuffs  a  moderate 
rate  of  growth  may  be  secured,  but  that  few,  if  any,  young  will 
ever  be  produced  if  the  mixture  fed  contains  more  than  50  per 
cent  or  less  than  10  per  cent  of  alfalfa  leaf.  The  importance 
of  combining  the  natural  foods  in  the  right  proportions  is  easily 
seen  from  these  results.  It  is  interesting  to  note  further,  that 
shifting  the  proportions  of  maize,  peas  and  leaf  in  this  mixture 
over  a  range  of  20  per  cent  does  not  materially  change  the  pro- 
tein content,  or  indeed,  the  chemical  composition  of  the  food 
mixture  to  a  degree  that  could  be  expected  to  make  so  great  a 
difference  in  the  state  of  nutrition  of  the  animals  as  is  actually 
observed. 

There  are  now  available  the  results  of  a  very  extensive  series 
of  feeding  trials  in  which  the  rations  were  made  up  of  one  seed, 
one  leaf  and  one  legume  (pea,  bean)  in  various  proportions  (8). 
These  have  failed  to  reveal  any  mixture  which  is  quite  the  equal 
of  the  first  ration  of  this  type  ever  employed,  that  composed  of 
maize  50  per  cent,  alfalfa  leaf  30  per  cent,  and  peas  20  per 
cent.  It  is,  of  course,  easily  possible  that  better  mixtures  of 
vegetable  foods  may  be  found  by  further  effort  but  these  results 
show  very  definitely  that  for  the  omnivorous  type  of  animal, 
whose  digestive  tract  is  so  constituted  that  the  consumption  of 
large  volumes  of  leafy  foods  is  not  possible,  it  is  by  no  means  a 
simple  matter,  to  derive  the  diet  entirely  from  the  vegetable 
foods,  and  secure  the  optimum  of  well-being.  The  data  afforded 
by  the  experiments  described  form  a  demonstration  of  the  fact 
that  wide  variety  is  of  little  value  as  a  safeguard  to  nutrition. 
Chemical  analysis,  no  matter  how  accurate  and  thorough,  fails 
to  throw  much  light  upon  the  dietary  value  of  a  food-stuff.  The 
only  way  in  which  the  problems  of  nutrition  can  be  solved  is 
through  numerous  and  properly  planned  feeding  experiments. 
Such  studies,  however,  were  not  possible  before  the  solution  of 
the  problem  of  successfully  feeding  mixtures  of  purified  food- 


168      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

stuffs.  These  led  to  the  formulation  of  an  adequate  working 
hypothesis  regarding  what  factors  operate  to  make  an  adequate 
diet,  and  made  possible  the  interpretation  of  the  cause  of  success 
or  of  failure  with  diets  of  the  complexity  employed  in  daily  life. 
It  will  be  shown  later  that  the  consumption  of  milk  and  its 
products  forms  the  greatest  factor  for  the  protection  of  mankind 
in  correcting  the  faults  in  his  diet. 

173.  The  Deficiencies  in  Inorganic  Elements  in  Seeds  Are 
Quantitative  Rather  Than  Qualitative. — The  cereal  grains  con- 
tain every  inorganic  element  found  in  the  animal  body,  and 
every  one  which  is  a  necessary  component  of  the  diet,  but  in  too 
small  amounts  in  respect  to  three  to  enable  the  animals  to  grow. 
That  insufficient  mineral  matter  in  a  diet  may  produce  grave 
pathological  conditions  reveals  this  moiety  in  a  new  and  im- 
portant light.    The   animal   is   sensitive  either  to  the  actual 
amounts  of  certain  of  the  mineral  elements  in  the  food  mixtures, 
or  to  the  relationships  among  them.    Sidney  Ringer  was  led  in 
1891  to  his  description  of  Ringer's  solution,  as  the  result  of  the 
observation  that  muscle  behaves  more  nearly  normally  in  solu- 
tions containing  certain  salts  in  definite  proportions.    Ringer's 
solution  contains  for  each  one  hundred  molecules  of  sodium 
chlorid  two  molecules  of  calcium  chlorid  and  between  one  and 
two  molecules  of  potassium  chlorid,  together  with  a  trace  of  a 
magnesium  salt.    Loeb,  Howell  and  others  have  described  many 
experiments  showing  the  profound  effects  upon  the  subsequent 
development  of  the  eggs,  of  varying  in  certain  ways  the  com- 
position of  the  salt  solutions  in  which  unfertilized  eggs  of  cer- 
tain marine  animals  were  kept  (9).    In  this  way  the  earliest 
stages  of  development  which  are  ordinarily  observed  only  in  the 
fertilized  egg  could  be  caused  to  take  place  in  eggs  into  which 
no  sperm  had  entered.    In  the  nutrition  of  the  higher  animals 
it  had  never  been  made  clear  how  dependent  the  organism  is  on 
the  rate  at  which  the  blood  stream  receives  mineral  nutrients. 
The  fact  that  the  cereal  grains  are  too  low  in  three  inorganic  ele- 
ments to  admit  of  growth  made  it  surprisingly  clear  that  food 
packages  just  as  they  come  from  the  hand  of  Nature  are  not 
necessarily  so  constituted  as  to  promote  health. 

174.  Vegetarianism  Has  Been  Viewed  from  the  Wrong 
Angle. — In  the  light  of  what   has  been  presented  in  this  chapter 
it  will  be  readily  appreciated  that  in  the  past  the  vegetarian  diet 
has  been  discussed  from  the  wrong  perspective.    It  is  possible 
to  make  a  fairly  satisfactory  diet  of  foods  entirely  derived  from 


THE  VEGETARIAN  DIET  169 

vegetable  sources,  but  it  is  not  easy  to  do  so.  In  general,  a 
vegetable  diet  will  be  markedly  improved  by  the  inclusion  of 
muscle  tissue  meats,  and  more  so  by  the  addition  of  glandular 
organs,  but  even  these  features  of  the  subject  are  not  from  the 
standpoint  of  good  nutrition  the  most  important.  It  is  scarcely 
practicable  for  man  to  eat  enough  leafy  foods  to  enable  him  to 
succeed  with  the  strictly  vegetable  diet.  The  limiting  factor  is 
the  amount  of  leafy  food  which  can  be  consumed.  Lack  of  suf- 
ficient  calcium  is  one  of  the  most  important  deficiencies  in  such 
a  diet,  and  a  great  abundance  of  leaf  is  necessary  to  supply  this 
element  in  adequate  amounts. 

175.     Some  Characteristics  of  Vegetarian  Diets. — The  diet 

la-    (y 


which  is  strictly  vegetarian  will  practically  always  be  of  rela 
tively  low  protein  content.  The  addition  of  even  small  amounts 
of  meat,  even  of  the  muscle  variety  will  be  very  valuable  when 
such  a  regimen  is  adhered  to.  Eggs,  because  of  their  relative 
richness  in  fat-soluble  A  and  water-soluble  B,  will  be  even  more 
effective  supplements,  and  the  same  statement  will  apply  to  the 
consumption  of  small  amounts  of  glandular  organs.  Even  small 
additions  of  foods  of  animal  origin  will  tend  therefore,  to  enhance 
the  diet  of  one  who  is  forced  by  economic  circumstance^  rather 
than  by  ethical  considerations,  to  subsist  in  the  main  upon 
vegetable  foods.  In  another  connection  we  shall  present  data 
showing  that  a  diet  too  low  in  protein  or  in  which  the  proteins 
are  of  relatively  poor  quality,  exerts  very  deleterious  effects  upon 
experimental  animals. 

Among  the  peoples  of  China  and  Japan  who  because  of  pov- 
erty and  overcrowding  can  afford  but  small  additions  of  fish, 
poultry  or  the  flesh  of  mammals  to  their  diet  consisting  in  great 
measure  of  vegetable  foods,  children  are  schooled  from  an  early 
age  to  the  consumption  of  leafy  vegetables.  Many  weeds  are 
eagerly  sought  after,  and  trees  are  stripped  of  their  buds  in 
spring  to  augment  the  supply  of  spinach,  cabbage  and  other  leafy 
foods.  An  alfalfa  field  seeded  by  a  missionary  (10)  in  north 
central  China  was  eagerly  appropriated  for  human  food,  although 
it  had  been  intended  to  serve  as  a  forage  for  farm  animals.  Mil- 
lions of  people  in  Asia  have  learned  the  unique  nutritive  value 
of  green  plants,  which  we  in  America  have  never  learned  to  ap- 
preciate. 

176.  Certain  Mineral  Elements  Are  Essential  to  Normal 
Functioning  of  the  Tissues.— So  much  has  been  said  in  these 
pages  of  the  importance  of  a  suitable  content  of  the  mineral  ele- 


170      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

ments  which  the  diet  must  furnish,  that  a  few  words  of  explana- 
tion as  to  the  functions  which  they  exercise  in  physiological 
processes  may  be  of  value  to  many  readers,  who  are  not  physiolo- 
gists or  chemists. 

Since  the  bones  consist  in  great  part  of  calcium,  phosphate  and 
magnesium  the  necessity  for  an  adequate  supply  of  these  ele- 
ments is  easy  to  appreciate.  Calcium  salts  are  essential  for  the 
coagulation  of  the  blood  as  it  flows  from  a  wound.  When  this 
element  is  removed  from  a  sample  of  blood  it  cannot  undergo 
clotting.  Certain  salts  of  calcium,  especially  the  chlorid,  greatly 
accelerate  the  rate  of  digestion  of  fats,  through  the  agency  of 
the  fat  digesting  enzymes,  or  lipases. 

For  purposes  of  normal  digestion  in  the  stomach  the  presence 
of  free  hydrochloric  acid  in  considerable  amounts  is  indispen- 
sable since  the  pepsin  cannot  act  upon  the  proteins  of  the  food 
unless  free  acid  be  present.  The  acid  of  the  stomach  is  derived 
from  the  sodium  chlorid  or  common  salt  of  our  food.  A  liberal 
supply  is  necessary,  and  notwithstanding  that  the  foods  all  con- 
tain a  certain  amount  of  it  we  are  impelled  by  our  appetites  to 
make  liberal  additions  of  it  in  cookery,  and  as  we  eat,  we  "salt 
to  taste." 

The  element  sodium,  which  is  a  constituent  of  common  salt, 
is  also  present  in  the  blood  in  considerable  amounts  in  the  form 
of  the  bicarbonate,  carbonate  and  phosphate.  These  act  as 
"buffer"  substances,  i.  e.,  they  take  up  and  neutralize  the  acids 
formed  during  metabolism,  and  aid  in  maintaining  the  body  fluids 
in  a  state  of  neutrality  which  is  a  fundamental  condition  of  life. 

One  of  the  prominent  features  of  the  functioning  of  living 
protoplasm  is  the  presence  of  fluids  within  it  which  contain  nicely 
adjusted  amounts  of  certain  mineral  salts,  which  maintain  what 
is  known  as  osmotic  pressure  within  the  cells  and  between  them 
and  the  body  fluids. 

Potassium  is  a  constituent  of  all  tissues  of  the  body,  but  the 
relative  amounts  in  different  structures  varies  considerably. 
Only  when  there  is  a  certain  relation  between  the  potassium, 
sodium  and  calcium  concentration  in  the  blood  will  the  heart 
beat  normally.  Other  functions  of  the  mineral  elements  could 
be  mentioned,  in  the  performance  of  which  each  plays  a  specific 
role,  and  in  the  performance  of  which  one  element  cannot  be 
replaced  by  another  without  causing  disturbances  of  metabolism 
or  even  death. 

177.     Most  Foods  Are  Too  Poor  in  the  Element  Calcium. — 


THE  VEGETARIAN  DIET  171 

The  cereals,  tubers  and  roots  must  be  used  in  combination  with 
calcium-rich  foods  such  as  milk,  or  leaves,  and  the  addition  of 
meats  or  eggs  cannot  take  their  place.  The  best  type  of  diet  is 
one  which,  in  addition  to  moderate  amounts  of  cereals,  tubers, 
legume  seeds,  root  vegetables,  and  small  amounts  of  meats  and 
eggs,  contains  liberal  quantities  of  milk,  and  the  leafy  vegetables. 

Milk  supplements  any  diet  to  which  it  is  added,  in  respect  to 
the  quality  of  its  proteins,  its  inorganic  content,  and  its  content 
of  the  three  demonstrated  dietary  essentials  A,  B,  and  C,  whose 
natures  are  not  understood.  When  it  has  been  heated  it  lacks 
the  factor  C,  which  is  protective  against  scurvy.  Milk  is  defi- 
cient only  in  iron. 

Leafy  vegetables  possess  essentially  the  same  supplementary 
relations  to  other  foods  as  does  milk.  When  eaten  raw,  they  are 
excellent  preventives  of  scurvy,  but  when  cooked  they  lose  most 
of  this  property.  They  are  rich  in  iron. 

Eggs  have  much  the  same  supplementary  relations  to  other 
foods  as  has  milk,  except  that  they  are  deficient  in  calcium,  and 
do  not  contain  carbohydrate,  so  their  tendency  is  to  favor  putre- 
factive decompositions  in  the  intestine  rather  than  to  encourage 
fermentative  organisms  to  develop. 


BIBLIOGRAPHY 

1.  Jaffa,  M.  E.:     Further  investigations  among  fruitarians  at  the  Cali- 

fornia Agr.  Exp.  Sta.,  1901-1902.    U.  S.  Department  of  Agriculture, 
Bull.  No.  132. 

2.  Fisher,   I.:     The  influence   of  flesh-eating   on  endurance,   Yale   Med. 

Rev.,  March,  1907. 

3.  Kellogg,  J.   H.:    Diet   as  a  means  of   increasing   vital   resistance   in 

tuberculosis    with    special    reference    to   the    protein    ration,    Med. 

Review,  1909,  Feb.  13. 

Diet  and  Endurance  at  Brussels,  Science,  October,  1907. 

4.  Slonaker,  J.  R.:     Effect  of  vegetarian  diet  on  spontaneous  activity, 

rate  of  growth  and  longevity  of  the  albino  rat,  Leland  Stanford 
Junior  Publications,  University  Series,  1912. 

5.  McCollum,  E.  V.,  Simmonds,  N.,  and  Pitz,  W.:     The  vegetarian  diet 

in  the  light  of  our  present  knowledge  of  nutrition,  Amer.  Jour,  of 
Physiol.,  1916,  xli,  333. 

6.  McCollum,  Simmonds,   and  Pitz:     The   supplementary  dietary  rela- 

tionship between  leaf  and  seed  as  contrasted  with  combinations  of 
seed  with  seed,  Jour.  Biol.  Chem.,  1917,  xxx,  13. 

7.  Evvard,  J.   M.:     Is  the   appetite   of  swine   a  reliable   indication   of 

physiological  needs?  Proc.  Iowa  Academy  of  Sciences,  1915,  xxii,  375. 

8.  McCollum,  and  Simmonds:     Unpublished  data. 


172     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

9.  Loeb,  J.:     The  dynamics  of  living  matter,  New  York,  1906. 

Howell,  W.  H.:    An  analysis  of  the  influence  of  the  sodium,  potassium 
and  calcium  salts  of  the  blood  on  the  automatic  contractions  of 
heart  muscle,  Amer.  Jour.  Physiol.,  1901,  vi,  181. 
Howell,  W.  H.:     Vagus  inhibition  of  the  heart  in  its  relation  to  the 

inorganic  salts  of  the  blood,  Amer.  Jour.  Physiol.,  1906,  xv,  280. 
10.  Qoldingj  H.  W.  i  Personal  communication. 


FIG.  3. — This  cow  was  the  same  age  as  that  shown  in  Figure  1.  She  derived  her 
ration  entirely  from  the  wheat  plant  during  the  last  two-thirds  of  her  growing  period. 
This  ration,  when  submitted  to  chemical  analysis,  showed  almost  exactly  the  same 
composition  as  that  fed  to  the  cow  in  Figure  1.  Note  the  poor  nutritive  condition  of 
the  wheat-fed  cow.  It  has  not  been  possible  to  prepare  a  ration  solely  from  wheat 
products,  which  will  induce  good  nutrition  in  animals.  Figure  4  shows  the  typical 
appearance  of  the  calves  produced  by  cows  fed  upon  a  ration  properly  "balanced,"  but 
derived  entirely  from  the  wheat  plant,  and  containing  the  seed,  stem  and  leaf. 


FIG.  8. — This  photograph  shows  the  degree  of  success  which  has  been  attained  in  securing 
growth,  reproduction  and  rearing  of  young  in  an  omnivorous  animal,  the  rat,  with  a  diet  of 
strictly  vegetable  origin.  The  diet  is  described  on  page  161.  The  data  available  seem  to 
demonstrate  that  successful  diets  of  plant  origin  can  be  secured  only  when  the  leaf  of  the 
plant  is  a  prominent  constituent  of  the  diet.  Those  parts  of  the  plant  whose  functions  are 
those  of  storage  organs  (seeds,  tubers  and  roots),  do  not  serve  as  adequate  diets,  even  when 
there  is  a  wide  variety  in  the  food  supply.  The  leafy  structures  are  so  constituted  as  to 
correct  the  deficiencies  of  mixtures  of  seeds,  tubers  and  roots. 

The  albino  and  her  daughter  are  shown  above,  and  her  granddaughter  below.  Young  in 
the  fourth  generation  were  successfully  reared,  with  no  apparent  diminution  in  vitality. 


CHAPTER  VIII 
THE  DIETARY  DEFICIENCY  DISEASES 

Scurvy 

178.  The  Relation  of  the  Diet  to  Certain  Diseases  Has 
Long  Been  Suspected. — There  has  long  been  a  belief  among 
both  medical  and  non-medical  observers  that  certain  diseased 
conditions  were  the  result  of  the  continued  use  of  a  faulty  diet. 
Of  these  scurvy  has  long  been  the  most  definitely  attributed  to 
unsatisfactory  quality  in  the  food.  This  disease  is  known  to 
have  occurred  in  the  thirteenth  century  among  the  armies  of 
the  Crusaders  during  the  sieges  of  Cairo  and  Damietta.  The 
disease  was  doubtless  almost  entirely  restricted  to  soldiers  and 
prisoners  until  after  the  discovery  of  America.  This  event 
marked  the  beginning  of  long  voyages,  and  scurvy  began  to  take 
a  heavy  toll  of  life  among  mariners.  It  became  known  as  "the 
calamity  of  sailors"  because  of  its  frequency  on  shipboard.  A 
notable  instance  in  the  history  of  scurvy  was  the  voyage  of 
Jacques  Cartier  in  1536.  While  in  the  St.  Lawrence  River  he 
lost  from  scurvy  twenty-six  of  his  party,  and  saved  the  remainder 
by  the  use  of  a  beverage  made  from  an  infusion  of  pine  needles 
(1).  The  efficacy  of  fresh  fruits  and  vegetables  as  remedial 
agents  in  the  prevention  and  cure  of  scurvy  was  discovered  by 
common  experience,  and  became  sufficiently  established  so  that 
in  1795  the  British  navy  began  the  regular  administration  of  lime 
juice  to  all  sailors.  This  caused  the  disease  to  disappear  prac- 
tically in  the  service.  In  1865  the  British  Board  of  Trade 
adopted  with  equally  beneficial  results  a  similar  regulation. 
Scurvy  continued  to  be  a  menace  to  all  armies  until  the  last  few 
decades,  when  more  effective  regulation  of  the  rationing  of  sol- 
diers has  been  practiced  (2) .  Until  a  generation  ago  the  disease 
was  common  among  miserably  fed  convicts. 

173 


174     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

179.  Some  of  the  Symptoms  of  Scurvy. — Scurvy  develops 
gradually.    The  sufferer  loses  weight,  is  anemic,  pale,  weak  and 
short  of  breath.    The  gums  become  swollen,  bleed  easily,  and 
frequently  ulcerate.    The  teeth  loosen  and  may  drop  out.     Ne- 
crotic  areas  in  the  jaw  bone  may  result.    Hemorrhages  into  the 
mucous  membranes  and  the  skin  are  characteristic.     In  the  skin 
large  blue-black  spots  develop  after  trivial  injury,  or  even  spon- 
taneously.   The  ankles  become  edematous,  and  in  severe  cases 
there  develops  a  hard,  board-like  condition  of  the  skin  and  sub- 
cutaneous tissues.    Nervous  symptoms  of  various  types  are  seen, 
some  of  which  are  the  result  of  the  rupture  of  blood-vessels. 
There  follows  in  the  later  stages  of  the  disease,  headache,  con- 
vulsions and  delirium. 

1 80.  Lime  Juice  Occasionally  Proved  Disappointing  as  an 
Anti-scorbutic  Food. — Although  the  experience  of  the  British 
navy  and  of  several  Arctic  expeditions  had  thoroughly   con- 
vinced physicians  and  officers  of  ships  that  lime  juice  was  a 
specific  remedy  for  scurvy,  there  were  a  number  of  widely  known 
outbreaks  of  the  disease  which  kept  alive  the  idea  that  it  was 
not  necessarily  due  to  the  lack  of  some  essential  substance  in 
the  diet.     One  of  these  was  the  experience  in  1875-77  of  the  ex- 
pedition of  Sir  George  Nares  to  the  polar  regions  made  in  the 
two  ships,  the  Alert  and  the  Discovery.    The  crews  of  both  of 
these  suffered  severely  from  scurvy,  although  lime  juice  was 
regularly  administered  to  all  the  men.     It  appears  that  the  lime 
juice  carried  by  this  expedition  was  inferior,  and  was  probably 
adulterated.    The  history  of  this  and  other  early  events  in  the 
history  of  the  use  of  anti-scorbutic  foods  has  been  interestingly 
written  by  Alice  Henderson  Smith  (3). 

In  1895-96  the  British  Army  garrisoned  at  Chitral  in  India, 
suffered  severely  from  scurvy,  not  a  man  having  escaped  it,  not- 
withstanding the  fact  that  lime  juice  was  regularly  administered 
daily.  In  1902,  the  men  who  constituted  the  party  of  Captain 
Scott  in  his  voyage  to  the  Antarctic,  developed  scurvy  in  spite 
of  the  fact  that  they  were  well  supplied  with  West  Indian  lime 
juice.  On  this  occasion  the  men  were  saved  by  the  substitution 
of  fresh  seal  meat  for  canned  meats;  mustard  and  cress  were 
grown  for  consumption  in  the  raw  state,  and  the  consumption 
of  bottled  fruits  was  increased  as  far  as  possible.  It  may  be 
said  at  the  outset  that  the  juice  of  limes  grown  in  the  West 
Indies  has  been  shown  to  be  of  but  one  quarter  the  value  of  limes 
from  the  Mediterranean  region.  Doubtless  some  of  the  lime 


THE  DIETARY  DEFICIENCY  DISEASES          175 

juice  provided  in  those  cases  where  failure  of  protection  against 
scurvy  resulted,  was  due  to  adulteration,  or  to  the  heating  of  the 
juice  for  the  purposes  of  preservation.  It  is  now  known  that 
heating  tends  to  destroy  the  substance  which  gives  fresh  fruits 
and  vegetables  their  protective  value.  Recent  investigations 
have  also  shown  that  there  is  a  difference  in  the  protective  power 
of  fresh  and  preserved  meats.  Arctic  explorers  had  great  faith 
in  the  virtue  of  fresh  meat,  whereas  experience  proved  that  salted 
or  canned  meats  repeatedly  proved  ineffective. 

181.  Many  Lost  Faith  in  the  Efficacy  of  Lime  Juice  as 
an  Anti-scorbutic  Food. — The  occasions  when  scurvy  outbreaks 
were  observed  despite  the  regular  use  of  lime  juice,  were  widely 
advertised  and  aroused  in  the  minds  of  many  the  suspicion  that 
scurvy  might  not  be  due  to  lack  of  freshness  in  the  food.    A 
number  of  theories  were  advanced  to  explain  the  etiology  of  the 
disease.    Harley  and  Jackson   (4)   in  1900  accepted  the  view 
which  had  been  put  forth  by  Torup  of  Christiania,  that  scurvy 
resulted  from  eating  decomposed  meat,  and  was  a  kind  of  "pto- 
main"  poisoning.     It  is  easy  to  understand  that  this  view  seemed 
plausible.    The  sailors  in  times  when  the  disease  was  common 
were  restricted  essentially  to  a  diet  of  salt  meat  and  hard  tack. 
The  experiences  of  men  in  the  Arctic  regions  with  fresh  and  stale 
meats  confirmed  the  supposition  that  the  latter  were  inferior  to 
the  former.     Stefansson  (5)  has  recently  reported  his  own  ob- 
servations on  this  disease  in  the  far  North,  which  led  him  to 
conclude  that  a  factor  of  no  small  importance  was  the  consump- 
tion of  large  amounts  of  salt  with  salted  meats,  and  he  there- 
fore resorted  as  a  protective  measure  to  denying  salt  to  his  men. 

182.  Scurvy  Attributed  to  Acidity  of  the  Diet.— Sir  A.  E. 
Wright  (6)  compared  the  symptoms  of  scurvy  with  those  induced 
by  large  doses  of  mineral  acids,  and  from  their  similarity  drew 
the  deduction  that  the  syndrome  was  the  result  of  acid  intoxica- 
tion.   He  suggested  that  a  diet  of  cereals  or  of  meat  or  of  the 
two  classes  of  foods  used  in  conjunction  produces  scurvy  because 
they  both  contain  an  excess  of  mineral  elements  which  in  metab- 
olism are  converted  into  acids.    He  presented  data  on  the  chemi- 
cal composition  of  a  number  of  food-stuffs  which  seemed  to  afford 
strong  evidence  that   his   theory  was   correct.    The   following 
table  gives  the  composition  of  a  list  of  foods,  with  their  relative 
yields  of  acid  and  base  radicals  which  were  worked  out  by  Wright 
in  support  of  his  view.    The  values  represent  the  oxalic  acid 
equivalent  of  100  grams. 


176     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Acid  Food-stuffs. Alkaline  Food-stuffs. 

Oats  1.69  gm.      Carrot   0.61  gm. 

Barley    1.19  Turnip   0.32 

Beef    0.27  Potato    027 

Wheat    025  Onion  0.25 

Egg   0.20  Cow's  milk  0.17 

Rice  0.10  Ox  blood 0.13 

Maize  0.07  Peas    0.13 

Lemon  juice   0.12 

Neutral  Food-stuffs.  Orange  juice 0.12 

Sugar  Beans  0.07 

Fats  Sheep  blood    0.07 

It  should  perhaps  be  mentioned  that  the  presence  of  organic 
acids  in  certain  of  the  vegetable  foods  in  the  alkaline  list,  is  of  no 
significance  in  this  connection  because  these  are  destroyed  by 
oxidation  in  the  tissues.  / 

It  will  be  observed  that  those  foods  which  were  reputed  to  / 
prevent  or  cure  scurvy  all  fall  in  the  alkaline  group.  Wright 
believed  that  it  was  not  essential  for  the  diet  to  contain  fresh 
vegetable  foods  but  that  to  protect  against  scurvy  it  should  sup- 
ply the  necessary  amount  of  alkaline  radicals  to  make  the  diet 
as  a  whole  somewhat  basic.  He  explained  the  protection  of  the 
Samoyeds  of  Arctic  Russia  against  scurvy  as  a  result  of  their 
consumption  of  liberal  quantities  of  reindeer  blood. 

183.  The  Classic  Experiments  of  Hoist  on  the  Etiology  of 
Scurvy. — Modern  knowledge  of  the  etiology  of  scurvy  dates 
from  the  discovery  by  Hoist  and  Froelich  of  the  University  of 
Christiania  in  1912  (7)  that  guinea  pigs  readily  develop  the  dis- 
ease when  confined  to  a  diet  of  cereals  or  of  bread.  These  in- 
vestigators pointed  out  that  the  syndrome  thus  produced  was 
the  analogue  of  scurvy  in  man,  and  was  characterized  by  loosen- 
ing of  the  teeth,  inflammation  of  the  gums,  hemorrhages  in  the 
joints,  decalcification  of  the  epiphyses  of  the  long  bones,  and  the 
typical  histological  picture  of  the  bone  marrow.  They  observed 
that  exclusive  feeding  of  guinea  pigs  with  carrots,  turnips  or  dan- 
delion did  not  lead  to  this  pathological  condition,  although  ani- 
mals on  these  foods  suffered  comparable  losses  in  weight  (30-40 
per  cent).  They  found  that  the  introduction  of  small  amounts 
of  fresh  cabbage  or  carrots  or  other  fresh  vegetables  could  effect 
a  cure  of  animals  suffering  from  the  disease.  They  drew  the  con- 
clusion, which  later  investigators  have  abundantly  confirmed, 
that  the  cause  of  scurvy  lay  in  the  absence  of  a  certain  chemical 


THE  DIETARY  DEFICIENCY  DISEASES         177 

substance  from  the  "scorbutic"  diets.  They  were  able  to  show 
that  the  anti-scorbutic  substance  is  readily  destroyed  by  cook- 
ing or  drying. 

The  first  to  observe  the  development  of  scurvy  in  guinea  pigs 
as  the  result  of  restriction  to  a  faulty  diet  was  Theobald  Smith 
(8)  of  the  Rockefeller  Institute  for  Medical  Research.  In  1895  he 
described  this  condition  as  being  induced  by  limiting  these  ani- 
mals to  a  diet  of  oats  and  bran.  This  chance  observation  was 
not  followed  up  by  a  detailed  study,  and  it  remained  unnoticed 
for  more  than  twenty  years. 

184.  The  View  That  Scurvy  Is  Due  to  an  Infection.— The 
work  of  Hoist  and  his  co-workers  did  not,  however,  explain  the 
etiology  of  scurvy  to  the  satisfaction  of  all.  In  1916  Jackson 
and  Moore  (9)  made  the  remarkable  observation  that  guinea  pigs 
fed  a  diet  of  oats  and  milk  ad  libitum  develop  typical  scurvy. 
Bolle  (10)  was  apparently  the  first  to  mention  that  these  ani- 
mals become  scorbutic  when  fed  exclusively  on  raw  or  cooked 
milk.  Hart  and  Lessing  (11)  had  produced  scurvy  in  monkeys 
by  feeding  with  condensed  milk,  rice  and  dried  pignuts.  Milk 
is  known  to  be  a  complete  food  for  young  animals,  and  to  induce 
normal  growth  for  months  during  the  suckling  period  when  it 
constitutes  the  sole  source  of  nutriment.  This  naturally  sug- 
gested that  some  factor  other  than  diet  entered  into  the  etiology 
of  the  disease.  Jackson  and  Moore  were  able  to  isolate  after 
death  a  diplococcus  from  the  tissues  of  scorbutic  guinea  pigs. 
These  organisms  cultivated  in  the  laboratory  and  subsequently 
innoculated  into  pigs  kept  on  a  normal  diet  capable  of  maintain- 
ing health,  produced  hemorrhages.  The  organisms  were  some 
weeks  later  again  isolated  from  the  lesions.  These  findings 
seemed  to  afford  strong  evidence  that  scurvy  may  be  induced  by 
bacterial  infection  (12). 

184.  McCollum  and  Pitz  Drew  Faulty  Deductions  from 
Their  Experiments  on  Scurvy. — The  significance  of  the  obser- 
vation that  guinea  pigs  develop  scurvy  when  fed  on  oats  and 
milk  seemed  even  more  important  to  McCollum  and  Pitz  (13) 
than  to  Jackson  and  Moore.  McCollum  and  Davis  (14)  had  in 
1915,  as  the  result  of  extensive  studies  on  the  nutrition  of  the  rat, 
formulated  the  working  hypothesis  that  the  simplest  diet  which 
can  support  normal  nutrition  in  this  species  is  one  which  fulfills 
the  following  conditions.  It  must  contain  sufficient  protein  of  the 
"complete"  type;  adequate  amounts  of  nine  mineral  elements 
in  appropriate  combinations  (Na,  K,  Ca,  Mg,  Cl,  P,  S,  Fe,  I) ;  a 


178     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

source  of  the  carbohydrate  glucose,  and  two  dietary  factors  of 
undetermined  chemical  nature,  which  McCollum  and  Kennedy 
(15)  provisionally  called  fat-soluble  A  and  water-soluble  B. 
These  were  recognized  as  belonging  to  the  class  of  food  substances 
which  Funk  (16)  had  designated  by  the  term  "vitamine,"  and  for 
the  existance  of  which  he  had  positive  evidence  only  in  the  case 
of  the  anti-beri-beri  substance  (water-soluble  B)  with  which 
polyneuritis  in  birds  and  beri-beri  in  man  had  been  successfully 
treated.  The  history  of  the  investigations  which  led  to  the  dis- 
covery of  these  has  been  presented  in  Chapter  II. 

McCollum  had  found  that  a  diet  of  oats  and  milk  sufficed  to 
maintain  a  rat  in  a  state  of  health  for  a  long  period,  without  any 
evidence  of  disease.  When  McCollum  and  Pitz,  independently 
of  Jackson  and  Moore,  observed  that  guinea  pigs  confined  to  a 
diet  of  oats  and  milk  quickly  succumb  to  scurvy,  they  found  it 
difficult  to  believe  that  the  disease  could  be  due  to  the  lack  of  a 
specific  substance,  for  milk  alone  suffices  as  the  sole  food  for  all 
young  mammals  during  a  critical  period  of  their  lives.  It  was 
difficult  to  accept  the  view  that  anything  essential  for  normal 
nutrition  was  absent  from  milk  and  oat  mixtures. 

They  further  observed  that  their  guinea  pigs  which  were  suf- 
fering from  scurvy  developed  impaction  of  the  cecum  when  the 
condition  was  brought  about  by  feeding  milk  and  oats,  both  of 
which  are  constipating  foods.  They,  therefore,  offered  the  tenta- 
tive explanation  that  injury  to  the  cecum  of  this  species  is  of 
primary  importance  as  a  factor  in  the  etiology  of  scurvy.  They 
were  inclined  to  accept  the  view  of  Jackson  and  Moore  that  the 
cause  of  the  disease  was  an  invasion  of  the  tissues  by  bacteria, 
made  possible  by  the  damage  to  the  cecum  as  a  result  of  the 
retention  of  feces.  The  observation  that  paraffin  oil  or  cathar- 
tics sometimes  saved  scorbutic  animals  from  death  lent  support 
to  this  view. 

185.  The  Earlier  Views  of  Hess  and  Unger  on  the  Cause 
of  Scurvy. — Immediately  after  the  appearance  of  the  paper  of 
McCollum  and  Pitz,  Hess  (17)  presented  a  study  of  infantile 
scurvy  which  seemed  to  support  strongly  the  view  that  scurvy 
is  not  simply  a  deficiency  disease.  He  observed  that  infants  fed 
milk  which  had  been  pasteurized  at  145  degrees  for  thirty  min- 
utes did  not  develop  scurvy,  whereas  others  fed  the  same  milk 
but  which  had  been  allowed  to  age  for  twenty-four  hours  on  ice 
did  so.  Milk  which  had  been  pasteurized  at  165  degrees  was 
found  to  be  more  likely  to  induce  scurvy  than  milk  which  had 


THE  DIETARY  DEFICIENCY  DISEASES          179 

been  pasteurized  at  the  lower  temperature.  Hess  also  found  that 
aging  of  raw  milk  also  increased  its  liability  to  induce  scurvy  in 
infants.  The  degree  of  heat  to  which  the  milk  had  been  sub- 
jected seemed  not  to  be  the  most  important  factor,  for  according 
to  his  experience  boiled  milk  did  not  produce  the  disease.  The 
most  plausible  deduction  from  these  observations  appeared  to  be 
that  boiling  tended  to  render  the  milk  sterile,  whereas  heating 
to  165  degrees  killed  for  the  most  part  the  lactic  acid  forming 
bacteria,  leaving  the  more  resistant  spore-forming  organisms  in 
the  milk,  where  they  could  develop  rapidly  because  with  aging 
the  lactic  acid  content  would  not  rise  and  hold  them  in  check  as  is 
the  case  in  milk  which  is  soured  in  the  normal  manner.  Milk 
which  was  pasteurized  at  145  degrees,  and  milk  which  was  aged, 
both  developed  flora  which  might  with  reason  be  supposed  to  be 
detrimental  to  an  infant.  Hess  drew  the  conclusion  that  it  was 
the  staleness,  and  therefore  the  bacteriological  condition,  rather 
than  the  temperature  to  which  the  product  had  been  heated, 
which  determined  whether  or  not  milk  would  tend  to  cause  scurvy 
in  the  infant. 

As  the  result  of  later  studies,  however  (18),  Hess  was  led  to 
abandon  this  theory  and  to  accept  the  view  that  scurvy  is  a  de- 
ficiency disease,  and  that  it  is  prevented  or  cured  by  the  admin- 
istration of  an  anti-scorbutic  substance. 

The  appearance  of  these  papers  aroused  a  number  of  investi- 
gators to  renew  the  study  of  the  etiology  of  scurvy,  and  the  vari- 
ous theories  concerning  the  etiology  of  the  disease  soon  were 
subjected  to  the  test  of  new  experiments.  Two  papers  among 
these  deserve  special  consideration  since  they  completely  ex- 
plained the  errors  into  which  several  workers  had  fallen,  and 
fully  established  the  correctness  of  the  view  of  Hoist  that^scurvy 
is  indeed  a  deficiency  disease  of  a  specific  nature. 

186.  Chick  and  Hume  Confirm  the  Views  of  Hoist.— In  1917 
Chick  and  Hume,  of  the  Lister  Institute,  extended  the  observa- 
tions of  Hoist  and  his  co-workers  by  making  a  comparative  study 
of  the  values  of  a  number  of  food-stuffs  as  protectives  against 
scurvy  (19).  There  are  two  methods  which  may  be  employed 
for  the  study  of  such  a  problem.  One  is  to  employ  animals  of 
a  definite  and  uniform  size  and  add  to  a  scorbutic  diet  a  certain 
amount  of  the  food  under  examination  to  discover  whether  or 
not  the  animals  are  protected  from  the  disease.  The  alternative 
is  to  produce  first  the  condition  and  then  attempt  to  relieve  the 
animals  by  the  administration  of  the  food,  the  anti-scorbutic 


180     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

properties  of  which  are  under  investigation.  Chick  and  Hume 
adopted  the  preventive  type  of  experiment.  They  fed  their  ani- 
mals oats  and  bran,  which  they  found  would  in  about  three  weeks 
produce  scurvy  in  a  guinea  pig  weighing  about  280  grams.  The 
substance  to  be  studied  was  added  in  known  amount  and  the 
duration  of  the  protection,  if  any,  observed. 

Chick  and  Hume  emphasized  the  superiority  of  this  method 
over  the  curative  type.  In  the  latter  the  animals  return  to  nor- 
mal slowly  even  when  the  anti-scorbutic  potency  of  the  diet  is 
made  high,  and  their  improvement  is  less  well  marked  when  it 
is  low.  This  method  leads  to  confusion  in  interpretation  of 
results. 

As  the  outcome  of  their  studies  Chick  and  Hume  constructed 
a  table  (see  page  181)  in  which  the  protective  values  of  a  num- 
ber of  foods  are  compared.  For  comparison  they  likewise  in- 
cluded such  data  as  is  available  to  indicate  the  content  of  each 
of  the  foods  in  the  anti-beri-beri  dietary  factor  (water-soluble 
B).  The  latter  information  was  gained  by  tests  of  the  curative 
type  on  pigeons  in  which  polyneuritis  was  developed  by  restric- 
tion to  a  diet  of  polished  rice. 

In  a  later  paper,  Chick,  Hume  and  Skelton  (20)  discussed  their 
experimental  work  in  relation  to  the  views  which  had  been  ex- 
pressed by  the  several  investigators,  who  held  that  scurvy  was 
not  a  deficiency  disease  in  the  same  sense  as  beri-beri  or  poly- 
neuritis.  In  the  light  of  their  data  the  erroneous  conclusions  of  ., 
McCollum  and  Pitz  were  explained.  It  was  shown  that  the  anti-  * 
scorbutic  value  of  milk  had  been  greatly  over-rated.  Chick  and 
her  co-workers  adopted  hand  feeding,  instead  of  allowing  the 
guinea  pigs  to  eat  of  milk  ad  libitum,  and  showed  that  when  less 
than  50  c.c.  of  raw  milk  daily  supplemented  a  diet  of  oats  and 
bran  it  did  not  defer  death  from  scurvy  beyond  thirty  days  or 
thereabouts.  When  50  c.c.  of  raw  milk  were  actually  consumed 
daily  the  life  of  the  animals  was  extended  to  about  seventy-five 
days.  An  intake  of  100  to  150  c.c.  of  milk  daily  served  to  main- 
tain the  animals  in  a  state  of  health  during  a  period  of  sixteen 
weeks,  at  which  time  the  observations  were  discontinued. 

187.  Milk  Not  a  Very  Effective  Anti-scorbutic  Food.— It 
is  necessary,  therefore,  that  the  diet  should  consist  almost  en- 
tirely of  milk  if,  through  its  agency  alone,  scurvy  is  to  be  pre- 
vented. Chick,  Hume  and  Skelton  point  out  that  this  concept  is 
consistent  with  the  role  played  by  mammalian  milk,  which  is 
destined  to  form  a  complete  food  for  a  definite  but  limited  period 
in  the  life  of  the  young. 


THE  DIETARY  DEFICIENCY  DISEASES 


181 


TABLE  XI 

VALUE  OF  FOODSTUFFS  AS  PREVENTIVES  AGAINST  SCURVY  AND  BERI-BERI 
—  SIGNIFIES  NOT  INVESTIGATED 


Foodstuffs. 

Water  Con- 
tent (Ap- 
prox.)  Per 
Cent. 

Value 
Against 
Beri-beri. 

Value 
Against 
Scurvy. 

Cereals  — 

Whole  grain  (wheat) 

r 

-f-  -|- 

0 

EndosDerm/P°lished  rice 
m  \white  flour  (wheat) 

jo 

0 

r,r      fe.g.,  rice 
Branje.g.,  wheat 

'  10  to  13 

{+  + 

0 

^.                            fe.  g.,  rice 
Germ  or  embryoj  e  g  ^  wheat 

{+  +  + 

0 

Pulses- 

Whole  (in  dry  condition) 

12 

+  + 

0 

Germinated  pulses  (or  cereals) 

50 

+  -I- 

+  +  + 

Vegetables  — 

Potatoes 

80 

0 

-l~  + 

fe.g.,  cabbage 
Fresh-j  e.  g.,  onions 
le.  g.,  carrot 

\  90 

+ 

+++ 

Desiccated  vegetables 

10  to  15 

4- 

-f-  to  0  ac- 

cord, to  age 

Pickled,  e.g.,  cabbage 

— 

— 

0 

Fruit  Juices  — 

5  \e.  g.,  lemon 

joo 

— 

+  +  + 

Eggs- 

Fresh 

70 

_l_  _j- 

— 

Desiccated 

6 

+4- 

0 

Meat  — 

Fresh 

/70 

-i- 

4- 

Tinned 

\ 

0 

0 

Milk- 

Cow's  (fresh) 

87 

0 

+  (slight) 

Yeast- 

Pressed  (autolysed) 

77 

+  +  + 

0 

Yeast— 

Extract  (commercial  sample  A) 

30 

+  +  + 

0 

There  is  a  remarkable  difference  between  the  value  of  certain 
fresh  vegetables  as  contrasted  with  milk,  for  the  protection  of 
animals  against  scurvy.  Chick  and  her  co-workers  found  that 
3  c.c.  of  fresh  orange  juice  or  2.5  to  5  grams  oi  fresh  cabbage 


182     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

leaves  when  added  daily  to  a  diet  of  oats  and  bran  were  suf- 
ficient to  prevent  the  development  of  the  symptoms  of  the  dis- 
ease. These  amounts  of  vegetables  were  equivalent  for  the  pre- 
vention of  scurvy,  to  about  100  c.c.  of  fresh  whole  milk  which 
had  not  been  heated. 

These  studies  offer  a  satisfactory  explanation  of  the  observa- 
tions of  McCollum  and  Pitz  who  found  that  guinea  pigs  which 
were  in  the  early  stages  of  acute  scurvy  and  at  the  same  time 
badly  constipated  as  the  result  of  an  exclusive  diet  of  oats  and 
milk,  could  in  some  cases  be  cured  by  the  administration  of  paraf- 
fin oil.  Harden  and  Zilva  (21)  pointed  out  that  any  ameliora- 
tion brought  about  by  the  administration  of  this  laxative  was 
due  to  the  increased  consumption  of  milk  because  of  the  clearing 
of  the  alimentary  tract,  and  consequent  improvement  in  the  well- 
being  of  the  animals. 

1 88.  The  Rat  and  Certain  Other  Species  of  Animals  Are 
Immune  to  Scurvy. — Mention  has  already  been  made  of  the 
several  factors  that  must  be  furnished  by  the  diet  in  order  to 
render  it  adequate  for  the  nutrition  of  the  rat  (14).  It  has  not 
been  found  possible  to  produce  experimental  scurvy  in  this  spe- 
cies, and  it  is  necessary,  therefore,  to  conclude  that  the  rat  either 
does  not  require  the  anti-scorbutic  substance  in  its  metabolic 
processes,  or  has  the  capacity  to  produce  the  substance  syn- 
thetically from  some  other  complexes  in  the  food.  If  the  latter 
assumption  be  true  the  nutrition  of  this  animal  would  be  inde- 
pendent of  this  factor. 

In  order  to  determine  which  of  these  explanations  holds  for 
the  immunity  of  the  rat  from  scurvy  several  decisive  experiments 
were  carried  out  in  my  laboratory  in  the  following  way  (22) : 
A  group  of  young  rats  were  fed  a  diet  of  purified  food-stuffs  sup- 
plemented with  an  alcoholic  extract  of  wheat  germ  to  furnish  the 
anti-beri-beri  factor,  water-soluble  B.  They,  therefore,  did  not 
have  access  to  the  anti-scorbutic  factor  C,  since  this  is  absent 
or  nearly  so  from  wheat  germ.  To  make  sure  of  this  fact  the 
extracts  were  heated  so  as  to  destroy  any  traces  which  may  have 
been  present  in  the  beginning.  These  rats  grew  to  the  full  adult 
size,  and  remained  in  good  health  to  the  age  of  fifteen  months  on 
a  diet  which  would  induce  within  ten  to  twenty-five  days  the 
severest  type  of  scurvy  in  young  guinea  pigs.  At  this  point  some 
of  the  rats  were  killed  and  their  fresh  livers  were  fed  to  young 
guinea  pigs  which  had  been  caused  to  develop  scurvy  as  the  re- 
sult of  a  faulty  diet.  In  this  manner  several  animals  were  com- 


THE  DIETARY  DEFICIENCY  DISEASES          183 

pletely  cured  of  scurvy  by  the  livers  of  rats  which  lacked  the 
anti-scorbutic  substance  in  their  diet.  There  can  be  but  one  con- 
clusion from  such  a  result.  The  rats  were  able  to  synthesize  the 
necessary  anti-scorbutic  substance  they  were  unable  to  secure 
from  their  food.  Otherwise  it  could  not  have  been  so  abundant 
in  the  liver.  Man,  guinea  pig  and  monkey,  however,  are  all  sus- 
ceptible to  scurvy  because  they  lack  the  synthetic  capacity  pos- 
sessed by  the  rat.  Another  example  of  a  species  which  is  able 
to  subsist  without  the  anti-scorbutic  substance  is  the  prairie  dog 
of  the  western  plains.  In  my  laboratory  a  young  prairie  dog 
born  in  captivity  was  restricted  soon  after  weaning,  to  a  diet 
which  would  certainly  produce  severe  scurvy  in  a  guinea  pig 
within  thirty  days.  Yet  the  animal  was  able  to  grow  in  a  nearly 
normal  manner  and  escaped  the  development  of  scurvy  during  a 
period  of  ten  months.  It  has  not  been  actually  demonstrated 
that  this  species,  like  the  rat,  has  the  power  to  synthesize  the 
missing  water-soluble  C,  for  the  possibility  remains  that  it  does 
without  it  without  detriment  to  its  health.  The  idea  that  its  case 
is  analogous  to  that  of  the  rat  seems  most  plausible. 

It  has  been  pointed  out  that  the  application  of  the  biological 
method  for  the  analysis  of  a  food-stuff  to  the  study  of  the  cereal 
grains  has  shown  that  these  are  deficient  in  three  important  re- 
spects and  are  individually  or  collectively  unsatisfactory  for  the 
nutrition  of  the  rat.  The  quality  of  their  proteins  is  below  the 
optimum ;  the  mineral  content  is  deficient  in  calcium,  phosphorus, 
sodium,  and  chlorin,  and  with  the  exception  of  yellow  maize 
and  millet  seed,  they  are  decidedly  low  in  fat-soluble  A.  Even 
when  the  latter  seeds  are  abundant  in  the  diet  the  content  of  fat- 
soluble  A  will  fall  decidedly  below  the  requirement  for  the  main- 
tenance of  nutrition  over  a  prolonged  interval,  or  the  amount 
necessary  to  meet  the  needs  of  a  female  during  the  period  of 
gestation  or  nursing. 

It  was  to  be  expected,  therefore,  that  investigators  should,  in 
the  light  of  these  studies,  appreciate  the  shortcomings  of  experi- 
ments of  the  older  type  in  which  it  was  customary  to  produce 
experimentally,  scurvy  in  guinea  pigs  by  restricting  the  diet  to 
cereals.  These  are  deficient  from  the  dietary  standpoint  as 
already  discussed  and  in  addition  are  not  of  a  physical  texture 
suitable  to  the  guinea  pig.  The  digestive  tract  of  this  animal  is 
fitted  only  for  a  diet  of  succulent  foods  such  as  green  grass,  roots 
and  leafy  vegetables.  When  these  are  eaten  in  liberal  amounts, 
grains  may  form  a  valuable  addition  to  their  diet,  but  not  other- 


184      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

wise.  Any  animal  which  possesses  so  highly  specialized  a  diges- 
tive tract  as  does  the  guinea  pig,  in  which  the  stomach  and  cecum 
are  very  large  and  delicate,  has  not  been  shown  to  be  satisfac- 
torily nourished  during  long  periods  on  a  diet  which  is  thor- 
oughly digested  and  absorbed,  and  which  leaves  little  residue,  or 
one  which  forms  hard  or  pasty  feces.  The  cereal  grains  leave 
little  residue,  and  oats  and  milk  form  hard  and  pasty  feces. 

189.  The  Studies  of  Cohen  and  Mendel  on  Scurvy. — In  or- 
der to  overcome  these  difficulties  Cohen  and  Mendel  (23)  pre- 
pared a  diet  of  cooked  soy  bean  flour  supplemented  with  3  per 
cent  each  of  sodium  chlorid  and  calcium  lactate,  and  dried  brew- 
er's yeast,  and  sufficient  raw  Jersey  milk  to  furnish  5  per  cent 
of  butter  fat.  The  yeast  was  added  for  the  purpose  of  procuring 
a  generous  amount  of  the  anti-beri-beri  substance,  water-soluble 
B,  and  butter  fat  for  the  object  of  furnishing  fat-soluble  A. 

On  this  diet,  which  contained  everything  necessary  for  the 
nutrition  of  the  guinea  pig  except  the  anti-scorbutic  substance, 
which  Drurnmond  designated  water-soluble  C  (24),  young  ani- 
mals gain  weight  very  rapidly,  and  for  a  time  their  appearance 
is  satisfactory.  On  about  the  tenth  day,  however,  while  still 
eating  well  and  gaining  in  weight,  they  begin  to  show  tenderness 
of  the  wrists  and  ankle  joints.  Their  condition  after  this  time 
rapidly  becomes  worse,  and  the  joints  swell  to  two  or  three  times 
their  normal  size.  The  appetite  fails  and  a  sharp  decline  in 
weight  ensues.  At  this  point  the  animals  can  be  saved  by  the 
administration  of  foods  containing  a  sufficient  amount  of  the 
anti-scorbutic  substance. 

Using  this  diet  Cohen  and  Mendel  were  able  to  confirm  the  ob- 
servations of  Hoist  and  of  Chick  and  her  co-workers,  and  to 
describe  what  appears  to  be  simple  scurvy  unaccompanied  by 
other  conditions  due  to  malnutrition.  Cohen  and  Mendel  have 
given  the  most  complete  and  accurate  description  of  the  syn- 
drome of  scurvy  in  the  guinea  pig.  Its  onset  is  usually  charac- 
terized by  tenderness  of  the  wrists,  ankles  and  knees,  developing 
in  the  order  named.  Within  a  day  or  two  the  affected  joints 
become  swollen,  frequently  to  the  extent  of  two  or  three  times 
the  diameter  of  the  normal  bone.  Spontaneous  fracture  of  the 
bones  is  of  frequent  occurrence.  These  conditions  are  observed 
especially  in  guinea  pigs  which  weigh  150  to  250  grams.  Older 
animals  lose  the  use  of  their  hind  legs  because  of  stiffening  and 
paralysis.  The  animals  find  relief  in  lying  on  the  side  or 
back  so  as  to  favor  the  affected  members.  This  position  has 


THE  DIETARY  DEFICIENCY  DISEASES          185 

been  described  by  Delf  (25)  as  the  "face-ache"  position.  If 
the  animals  are  permitted  to  remain  long  on  the  diet  deficient  in 
the  anti-scorbutic  substance  the  swellings  fail  to  disappear  when 
the  diet  is  corrected,  and  develop  into  exostoses.  When  curative 
measures  are  administered  early  enough  the  bones  appear  to 
return  to  normal. 

190.  The  Anatomical  Lesions  in  Scurvy. — The  two  most 
noticeable  conditions  observable  at  autopsy  are  hemorrhage  and 
fragility  of  J/he  bones.    The  stomach,  intestines  and  cecum  may 
sliow  congestion,  hemorrhage  or  ulceration,  but   according  to 
Cohen  and  Mendel  these  organs  may  in  some  cases  be  normal  in 
appearance.    These  pathological  conditions  are  usually  observed 
in  animals  fed  oats  and  water  or  oats  and  milk,  and  less  fre- 
quently in  those  fed  the  diet  of  Cohen  and  Mendel.    These 
authors  point  out  that  an  ever  present  condition  in  advanced 
scurvy  is  lack  of  appetite  for  food.    They  found  the  food  intake 
to  diminish  as  the  disease  advances,  but  that  fasting  does  not 
produce  the  characteristic  lesions  of  scurvy.    These  observations 
have  been  confirmed  by  Lewis  and  Kerr  (26). 

A  remarkable  observation  made  by  Mendel  and  Cohen  is  that 
the  swollen  joints  and  tenderness  often  appear  while  the  animalc 
are  still  growing  rapidly  and  enjoying  a  good  appetite.  Inani- 
tion can,  therefore,  play  but  a  minor  role,  if  any,  in  the  produc- 
tion of  the  more  prominent  symptoms  of  scurvy.  There  seems 
to  be  regularly  a  period  of  ten  days  or  so  of  fasting  previous  to 
the  death  of  the  animals  which  are  confined  to  the  scorbutic  diet 
of  soy  beans  or  cereals,  for  the  loss  in  weight  during  this  period 
corresponds  to  the  rate  noticed  in  guinea  pigs  during  starvation. 

191.  The  Anti-scorbutic  Values  of  Some  Common  Food- 
Stuffs. — It  remains  to  record  the  more  significant  experimental 
data  which  show  the  distribution  of  the  anti-scorbutic  substance, 
and  its  tendency  to  be  destroyed  by  heating,  drying  or  aging, 
and  its  synthesis  during  the  germination  of  seeds. 

Chick  and  Delf  (27)  studied  the  anti-scorbutic  values  of  dried 
peas  and  lentils  and  found  them  to  have  no  demonstrable  value. 
On  soaking  the  seeds  for  24  hours  in  water  and  germinating  for 
48  hours  at  room  temperature,  the  anti-scorbutic  value  became 
pronounced.  While  these  sprouted  seeds  were  found  to  be  in- 
ferior to  orange  or  lemon  juice,  or  to  cabbage  or  swedes,  they 
were  equal  in  efficiency  to  green  beans  or  potatoes,  and  superior 
to  carrots  or  beet  roots.  The  anti-scorbutic  power  is  greatly 
reduced  by  boiling.  For  this  reason  they  recommend  that  when 


186      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

any  green  food  is  being  depended  upon  to  protect  against  scurvy 
it  should  be  cooked  as  short  a  time  as  possible. 

Delf  (25)  showed  that  a  very  small  amount  of  raw  cabbage 
is  sufficient  to  protect  guinea  pigs  from  the  symptoms  of  scurvy 
when  added  daily  to  a  diet  of  grains  and  autoclaved  milk.  Her 
histological  evidence  showed,  however,  that  an  apparently 
healthy  animal  may  be  in  a  condition  of  incipient  scurvy  as  re- 
gards the  structure  of  its  growing  bones. 

192.  The  Effect  of  Heat  on  the  Anti-scorbutic  Value  of 
Cabbage. — Delf  employed  cabbage  which  had  been  subjected  to 
various  temperatures  for  different  lengths  of  time,  and  compared 
these  materials  with  raw  cabbage.    The  anti-scorbutic   factor 
was  found  to  be  very  sensitive  to  temperatures  below  100  de- 
grees C.     She  estimated  that  70  per  cent  of  the  original  value 
was  lost  after  one  hour's  heating  at  60  degrees,  and  over  90  per 
cent  after  the  same  treatment  at  90  degrees.    After  20  minutes 
heating  at  90  or  100  degrees  the  loss  was  about  70  per  cent  or 
the  same  as  at  60  degrees  after  one  hour.     She  further  pointed 
out  the  fact  that  the  rate  of  destruction  of  the  anti-scorbutic 
substance  in  cabbage  leaves  is  increased  only  about  three-fold 
for  an  increase  in  temperature  of  30-40  degrees,  would  be  an 
argument  against  the  view  that  the  heat  denaturization  of  an 
enzyme-like  body  is  in  question.     Delf  suggests  that  in  cooking 
green  vegetables  there  will  be  less  loss  of  anti-scorbutic  property 
through  cooking  a  short  time  at  a  higher  temperature  than  at  a 
lower  temperature  for  a  longer  period.     Her   experience  with 
cabbage  heated  at  100°  to  130°  C.  for  periods  of  one  to  two 
hours,  supplementing  the  diet  of  oats  and  bran,  indicates  that 
the   destruction   of  the   anti-scorbutic   substance,   though   pro- 
nounced, is  not  so  great  as  the  observations  of  Hoist  and  Froelich 
would  indicate. 

193.  Young  Carrots  Are  Better  Than  Old  as  Anti-scorbutic 
Food. — Hess  and  Unger   (28)   demonstrated  the  superiority  of 
young  over  old  carrots  for  the  protection  of  guinea  pigs  against 
scurvy.    They  likewise  found  that  carrots  cooked  in  an  open 
vessel  for  45  minutes,  no  longer  afforded  protection  when  33 
grams   of   old   carrots   were   fed.    The   same   amounts   of   un- 
cooked carrots  were  effective.    The  water  in  which  carrots  were 
cooked  had  little  if  any  anti-scorbutic  properties.    Young  and 
fresh  carrots  withstood  dehydration,  retaining  a  part  of  their 
curative  properties. 

194.  Effect  of  Drying  on  the  Anti-scorbutic  Value  of  Vege- 


THE  DIETARY  DEFICIENCY  DISEASES          187 

tables. — These  authors  found  that  a  daily  allowance  of  five 
grams  of  dried  vegetables,  added  to  a  diet  of  oats,  hay  and  water 
failed  to  protect  guinea  pigs  against  scurvy.  They  tested  a 
commercial  preparation  of  dried  vegetables;  carrots  dried  at 
room  temperature  in  summer,  and  carrots  dried  rapidly  at 
130°  F.  a  few  weeks  before  the  experiment.  None  of  these  pos- 
sessed much  anti-scorbutic  value.  A  watery  decoction  of  dried 
orange  peel,  on  the  other  hand,  was  able  to  protect  their  animals. 

195.  The  Effect  of  Aging  on  the  Anti-scorbutic  Value  of 
Orange  Juice. — Hess  and  Unger  (29)  found  fresh  orange  juice 
to  be  anti-scorbutic,  but  juice  which  had  been  preserved  in  a 
refrigerator  for  three  months  had  lost  a  considerable  amount  of 
its  potency.    Ten  minutes  heating  at  110°  C.  did  not  entirely 
destroy  the  value  of  the  juice  as  a  protective  against  the  disease. 

These  investigators  precipitated  fresh  orange  juice  with  95  per 
cent  or  with  absolute  alcohol,  and  found  the  solution  potent,  but 
the  residue  of  no  value.  Neutralized  orange  juice  given  sub- 
cutaneously  failed  to  protect  animals.  They  report  the  success- 
ful employment  of  orange  juice  given  intravenously,  after  it  had 
been  boiled  and  made  slightly  alkaline  to  litmus  by  the  addition 
of  normal  sodium  hydroxid  just  before  using. 

196.  Tomato  Withstands  Heating  Without  Complete  De- 
struction of  Its  Anti-scorbutic  Properties. — Hess  and  Unger 

(30)  obtained  good  results  with  canned  tomatoes  in  the  preven- 
tion and  treatment  of  experimental  scurvy  in  guinea  pigs.    They 
also  fed  canned  tomato  to  infants,  substituting  it  for  orange 
juice,  and  found  that  15  c.c.  per  day  were  well  tolerated  by  in- 
fants over  three  months  of  age.    They  recommend  this  as  an 
economical  and  efficient  anti-scorbutic  for  children.     It  appears 
that  the  tomato  withstands  heating  with  less  deterioration  of  its 
anti-scorbutic    property,   than    does    any    other   vegetable   yet 
studied.     Unfortunately  tomatoes  are  ordinarily  little  if  any 
cheaper  than  oranges,  and  canned  tomatoes  would  not  prove 
economical  except  in  institutions  where  an  entire  can  could  be 
used  at  once  after  opening. 

197.  Yeast  Has  Little  or  No  Anti-scorbutic  Value. — Hess 

(31)  found  yeast  to  be  without  value  for  the  protection  of  in- 
fants against  scurvy,  when  the  autolyzed  product  was  given  daily 
in  doses  of  15-30  c.c.    Wheat  germ  possesses  some  anti-scorbutic 
value,  but  is  not  comparable  with  orange  juice.     He  points  out 
that   infants   may   develop   scurvy   while   gaining   steadily    in 
weight.    Hess  and  Unger  (32)  have  described  other  experiments 


188      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

which  seem  to  indicate  that  the  alkalization  of  foods  with  potas- 
sium carbonate  tends  to  destroy  their  anti-scorbutic  value. 

198.  Harden  and  Zilva's  Experiments  with  Lemon  Juice 
Preparations. — Harden  and  Zilva  (33)  made  from  lemon  juice 
a  preparation  nearly  free  from  citric  acid,  which  still  retained 
much  of  its  curative  power,  and  was  successfully  applied  thera- 
peutically  to  infants,  guinea  pigs  and  monkeys.    These  studies 
strengthen  the  conclusiveness  of  the  proof  that  the  disease  which 
is  produced  experimentally  in  animals  is  analogous  to  human 
scurvy. 

199.  Desiccated  Fruits  and  Vegetables  Are  of  Little  Value 
as  Anti-scorbutic  Foods. — Much  interest  has  centered  upon  the 
question  of  the  merits  of  desiccated  and  cooked  vegetables  as 
anti-scorbutic  foods.     Givens  and  Cohen  (34)  experimented  with 
cabbage  and  with  potatoes  which  had  been  cooked  and  dried  in 
an  air  blast  at  38-52°  C.  and  at  65-70°  C.    Their  results  show 
that  cabbage  dried  in  an  air  blast  at  40-52°  C.  retains  some  of 
its  protective  properties,  and  could  delay  the  onset  of  symptoms 
of  scurvy  and  prolong  life  when  animals  consumed  one  gram 
daily  as  a  supplement  to  a  scorbutic  diet. 

200.  Rate  of  Destruction  of  Anti-scorbutic  Value  of  Cab- 
bage During  Heating. — Cabbage  heated  in  an  oven  for  two 
hours  at  75-80°  C.,  then  dried  at  65-70°  C.  for  several  days  lost 
its  anti-scorbutic  properties.    Cabbage  cooked  for  30  minutes 
then  subjected  to  drying  for  two  days  at  65-70°  C.,  possessed  no 
protective  value  for  animals.    Potatoes  cooked  and  dried  for 
two  days  at  65-70°  C.  failed,  when  consumed  by  guinea  pigs 
to  the  extent  of  the  equivalent  of  5  grams  daily,  to  protect 
the  animals  against  scurvy. 

These  results  are  in  harmony  with  those  of  Delf  and  Skelton 
(35),  who  made  an  elaborate  study  of  the  value  of  dried  cab- 
bage as  an  anti-scorbutic  agent.  They  estimated  that  cabbage 
dried  at  a  low  temperature  and  stored  for  two-three  weeks,  lost 
more  than  95  per  cent  of  its  protective  value.  They  concluded 
that  desiccation  of  vegetables  is  an  economically  unprofitable 
process  on  account  of  the  deterioration  of  the  specific  value  of 
this  class  of  food-stuffs. 

20 1.  The  Anti-scorbutic  Value  of  Canned  Vegetables  and 
Fruits. — Campbell  and  Chick    (36)    studied  the   anti- scorbutic 
value  of  canned  foods.    The  cans  were  filled  with  vegetables, 
and  then  to  within  one-fourth  inch  of  the  top  with  boiling  water, 
and  at  once  hermetically  sealed  by  soldering  the  lids.    Steriliza- 


THE  DIETARY  DEFICIENCY  DISEASES          189 

tion  was  effected  by  exposure  to  steam  at  100°  C.  for  one  and 
a  half  hours.  The  cans  were  then  cooled  by  plunging  them  into 
cold  water,  and  were  stored  at  60-65°  F.  By  this  treatment  the 
anti-scorbutic  value  of  20  grams  of  bean  pods  was  reduced 
to  less  than  that  of  5  grams  of  fresh  material.  Seventy-five 
to  90  per  cent  of  the  protective  power  was  estimated  to  have 
been  lost.  Under  comparable  conditions  of  treatment  about  70 
per  cent  of  the  anti-scorbutic  value  of  cabbage  was  lost. 

202.  Anti-scorbutic  Value  of  Some  Indian  Dried  Foods. — 
Chick,  Hume  and  Skelton  (36)  tested  several  Indian  dried  fruits 
as  anti-scorbutics,  which  have  long  been  esteemed  by  the  native 
population  for  this  purpose.    Their  experiments  included  dry 
tamarinds,  cocum,  and  mango.    The  authors  concluded  that  these 
possessed  a  definite  but  small  anti-scorbutic  value.    This  was 
greatly   inferior  to  that  of  raw   cabbage,   swedes,   germinated 
pulses,  orange  juice  or  lemon  juice,  in  the  fresh  condition,  reck- 
oned weight  for  weight. 

203.  The  Anti-scorbutic  Value  of  Some  Concentrated  Fruit 
Juices. — Harden  and  Robison    (37)    studied  the  anti-scorbutic 
properties  of  concentrated  fruit  juices.    The  volatile  constituents 
of  orange  juice  were  found  to  be  valueless.     Orange  juice  was 
concentrated  to  a  syrup  under  reduced  pressure  at  40°  C.     One 
gram  of  this  dried  juice,  equivalent  to  9  c.c.  of  fresh  juice,  was 
fed  daily  during  forty  days  as  a  supplement  to  a  diet  of  oats, 
bran  and  autoclaved  milk.    After  this  the  amount  was  reduced 
to  one-half  gram,  or  the  equivalent  of  4.5  c.c.  of  juice  daily,  and 
the  experiment  continued  for  twenty-eight  days  longer.    The 
weight  of  the  guinea  pig  was  maintained  throughout  the  experi- 
ment, and  at  autopsy  no  evidence  of  scurvy  was  found.    When 
this  desiccated  orange  juice  was  preserved  during  seven  months, 
it  was  found  that  there  was  no  demonstrable  deterioration  as  the 
result  of  aging. 

Concentrated  lime  juice  was  prepared  by  a  rapid  process  in 
which  the  heating  was  continued  for  less  than  a  minute.  The 
resulting  syrup  was  preserved  with  twice  its  weight  of  sugar. 
The  authors  believe  that  the  loss  of  anti-scorbutic  property  of 
this  evaporated  juice  was  slight. 

Apple  juice  was  evaporated  rapidly  to  one-sixth  of  its  original 
volume,  within  one  minute.  The  maximum  temperature  reached 
was  102°  C.  The  resulting  jelly  was  found  to  possess  value  as 
an  anti-scorbutic  food,  but  the  deterioration  seemed  to  be  greater 
than  was  observed  in  the  case  of  orange  juice.  The  use  of  fruit 


190     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

jellies  prepared  by  this  method  was  recommended  where  there 
is  reason  to  suspect  a  deficiency  of  anti-scorbutic  substance  in 
the  diet. 

204.  Effect  of  Ultra- Violet  Light  on  the  Anti-scorbutic  Sub- 
stance.—Zilva  (38)  studied  the  effect  of  ultra-violet  light  on  the 
anti-scorbutic  substance.    Lemon  juice  which  had  been  brought 
to  a  H-ion  concentration  of  PH  2.34,  and  also  some  which  was 
made  neutral,  was  exposed  to  the  rays  for  8  hours  without  in- 
fluencing its  properties. 

205.  Raw  Lean  Beef  Possesses  No  Anti-scorbutic  Value. — 
Butcher,  Pierson  and  Biester   (39)    found  that  raw  lean  beef 
does  not  possess  anti-scorbutic  properties  sufficient  to  permit  of 
its  demonstration  by  experiments  with  guinea  pigs. 

206.  Raw  Potato  Is  a  Good  Anti-scorbutic  Substance. — 
Givens  and  McClugage  (40)  found  that  10  grams  of  raw  potato 
per  day  was  sufficient  to  protect  a  guinea  pig  from  scurvy.    A 
temperature  of  35-40°  C.  for  6  to  8  hours  seems  to  be  more 
destructive  of  the  anti-scorbutic  property  than  55-60°  C.  for 
4  to  6  hours,  and  the  latter  treatment  is  scarcely  as  destructive 
as  75°  to  80°  C.  for  2  to  3  hours.    The  influence  of  heat  appears 
to  be  related  not  only  to  temperature  reached  but  to  the  duration 
of  treatment,  the  reaction,  the  enzymes  present,  and  the  manner 
of  heating.    When  potatoes  were  baked  for  a  short  time  and 
then  dried,  the  resulting  product  possessed  protective  properties. 
These  observations  are  in  harmony  with  those  of  Hoist  and  also 
of  Chick. 

It  will  be  seen  from  the  foregoing,  that  the  anti-scorbutic  sub- 
stance is  a  relatively  unstable  body,  and  that  cooked  foods  are 
in  general  of  little  value  as  a  source  of  it.  The  tomato  appears 
to  be  a  notable  exception.  The  acidity,  or  other  condition  found 
in  the  juices  of  the  citrous  fruits,  serves  very  effectively  to  pre- 
serve the  anti-scorbutic  factor  in  its  physiologically  active  form 
during  heating  and  drying. 

207.  Relation  of  the  Food  of  the  Cow  to  the  Anti-scorbutic 
Value  of  the  Milk. — The  studies  relating  to  the  anti-scorbutic 
value  of  milk  are  of  special  interest  because  of  their  importance 
in  the  nutrition  of  infants.    It  was  shown  some  years  ago  by 
McCollum  and  Simmonds   (41)   that  neither  the  anti-beri-beri 
substance,  water-soluble  B,  nor  the  anti-ophthalmic  substance, 
fat-soluble  A,  are  present  in  the  milk  unless  they  are  supplied 
by  the  diet  of  the  lactating  animal.     If  this  should  be  true  of 
the  water-soluble  C  as  well,  it  is  obvious  that  the  nature  of  the 


THE  DIETARY  DEFICIENCY  DISEASES          191 

food  supply  of  cows  whose  milk  is  to  be  used  for  infant  feeding, 
when  it  serves  as  the  sole  source  of  the  protective  substance 
against  scurvy,  is  of  great  importance.  Several  investigations 
have  been  reported  which  were  directed  toward  the  solution  of 
this  problem. 

Barnes  and  Hume  (42),  Dutcher,  Pierson  and  Biester  (43)  and 
Hart,  Steenbock  and  Ellis  (44)  have  studied  this  problem.  The 
last-named  investigators  have  reported  studies  of  the  anti-scor- 
butic value  of  milk  of  cows  which  had  been  kept  on  dry  feed  for 
varying  periods,  as  contrasted  with  that  of  cows  which  were 
feeding  upon  green  pasture.  Summer  milk  was  found  to  be  much 
richer  in  this  respect  than  winter  milk.  Fifteen  c.c.  of  summer 
milk  afforded  protection  against  scurvy  to  a  guinea  pig  during 
20  weeks,  when  superimposed  upon  a  scorbutic  diet.  For 
most  individuals  it  was  found  that  as  much  as  50  c.c.  daily  were 
necessary  to  afford  complete  protection.  Of  winter  milk  from 
cows  which  had  been  fed  exclusively  on  dry  feed  for  many 
months,  70  c.c.  were  necessary.  Silage  or  sugar  mangels  added 
to  a  ration  of  dry  feeds  did  not  improve  the  anti-scorbutic  value 
of  the  milk  in  a  noticeable  degree.  Dutcher  and  his  co-workers 
(45)  found  20  c.c.  of  summer  milk  superior  to  60  c.c.  of  winter 
milk  in  its  anti-scorbutic  potency.  When  cows  were  changed 
from  a  ration  of  fresh  green  feed,  to  one  of  dry  grains,  hay  and 
fodder,  the  milk  did  not  fall  off  rapidly  in  its  anti-scorbutic 
value,  but  only  after  the  lapse  of  some  weeks  did  it  become 
inadequate  in  this  respect.  When  cows  were  changed  to  a  green 
pasture  after  a  long  period  on  a  dry  feed,  their  milk  very 
promptly  improved  in  a  marked  degree  in  its  value  as  an  anti- 
scorbutic agent. 

208.  Liberal  Amount  of  Fresh  Milk  Is  Essential  for  Pro- 
tection of  an  Infant  Against  Scurvy. — Hess  and  Unger  (46) 
state  that  an  infant  requires  fully  half  a  pint  of  unheated  milk 
daily  in  order  to  provide  it  with  an  adequate  amount  of  the 
dietary  factor  water-soluble  C.  If  the  milk  has  been  pasteur- 
ized, or  otherwise  heated  more  will  be  required  to  afford  protec- 
tion. Dutcher  has  recently  reported  that  milk  can  be  heated 
to  the  boiling  point  without  the  destruction  of  much  of  its  anti- 
scorbutic property  provided  it  is  kept  in  an  undisturbed  condi- 
tion. If  it  is  stirred  or  shaken  it  loses  its  value  in  this  respect 
very  rapidly.  The  explanation  for  this  appears  to  be  found  in 
the  destructive  effects  of  oxygen  on  the  vitamin  (47) . 


192      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

209.  Effect  of  Drying  on  the  Anti-scorbutic  Value  of  Milk. 
— Hess  and  Unger  (48)   state  that  drying  does  not  necessarily 
destroy  entirely  the  anti-scorbutic  value  of  milk.    The  tempera- 
ture and  time  of  drying,  and  the  condition  of  the  milk  at  the  time 
of  drying,  are  important  factors  in  determining  the  quality  of  the 
final  product  in  respect  to  its  scurvy-preventing  value.     Hart 
and  his  co-workers  (49)  have  presented  data  which  would  sup- 
port the  view  that  milk  which  has  been  dried  on  a  drum  retains 
more  of  its  anti-scorbutic  value  than  milks  which  have  been  dried 
by  the  spray  process.    The  data  presented  above,  showing  the 
results  attained  by  several  investigators  who  have  studied  the 
effects  of  heat  treatment  on  fruits  and  vegetables,  show  that  the 
method  of  study  is  not  sufficiently  accurate  to  warrant  confidence 
that  the  results  can  be  used  safely  as  a  basis  of  accurate  com- 
parisons.   Work  of  this  nature,  when  repeated,  is  likely  to  give 
results  more  or  less  at  variance  with  those  of  former  experi- 
ments.   The  only  safe  attitude  toward  the  use  of  dried  milks  in 
infant  feeding  is  to  insist  upon  the  addition  of  some  effective  anti- 
scorbutic food  such  as  orange  juice,  tomato  juice,  swede  juice, 
or  certain  other  vegetable  juices  which  agree  with  infants  or 
young  children.     It  does  not  seem  important  to  attempt  to  dif- 
ferentiate between  different  milk  powders  as  a  source  of  the  anti- 
scorbutic factor. 

210.  The  Diet  of  the  Nursing  Mother  Should  Contain  an 
Abundance  of  Anti-scorbutic  Foods. — Cow's  milk,  and  doubt- 
less human  milk  as  well,  has  relatively  low  anti-scorbutic  value 
even  when  derived  from  a  highly  satisfactory  diet.     It  suffices  to 
protect  the  young  when  the  diet  is  almost  wholly  derived  from 
milk.    When,  as  is  not  infrequently  done,  top  milk  is  employed, 
modified  by  dilution  and  the  addition  of  sugar  or  cereal  water, 
the  infant  may  be  placed  in  jeopardy  with  respect  to  the  develop- 
ment of  scurvy.     In  early  childhood,  the  displacement  of  any 
appreciable  amount  of  the  milk  diet  by  cereal  foods  is  a  step 
of  doubtful  expediency,  and  if  this  course  is  pursued,  fresh  fruit 
juices  should  never  be  omitted  from  the  diet  under  such  circum- 
stances. 

211.  Relation  of  the  System  of  Feeding  to  the  Incidence  of 
Scurvy  in  Infants. — Further  evidence  relating  to  the  importance 
of  the  mother's  diet  in  the  anti-scorbutic  value  of  her  milk  is 
afforded  by  a  report  made  by  a  committee  of  the  American 
Pediatric  Society  in  1898.    Among  356  cases  of  scurvy  in  infants 
10  were  infants  which  had  been  nursed.    The  following  table 


THE  DIETARY  DEFICIENCY  DISEASES          193 

gives  very  interesting  information  regarding  the  anti-scorbutic 
potency  of  milks  treated  in  different  ways  (50) . 

RELATION  BETWEEN  THE  KIND  OP  FOOD  AND  THE  INCIDENCE  OF  SCURVY 

Breast  milk    12  cases ;  alone  in  10 

Raw  cow's  milk   5  cases ;  alone  in    4 

Pasteurized   milk    20  cases ;  alone  in  16 

Condensed    milk    60  cases ;  alone  in  32 

Sterilized   milk    107  cases ;  alone  in  68 

Proprietary  infant  food  214 


The  above  data  point  clearly  to  the  easy  destruction  of  the 
anti-scorbutic  potency  in  milks  which  have  been  subjected  to 
manipulation.  The  occurrence  of  a  small  number  of  cases  among 
nursed  infants  shows  that  the  meat,  bread  and  potato  type  of 
diet  which  is  in  such  widespread  use  in  this  and  other  countries 
in  recent  times,  does  not  suffice  for  the  production  by  a  nursing 
mother  of  a  milk  which  is  complete  for  the  nutrition  of  her 
infant.  We  have  no  way  of  determining  how  large  a  number 
of  infants,  as  a  result  of  taking  breast  milk  of  poor  quality,  have 
reached  the  stage  of  borderline  cases  of  scurvy,  but  whose  con- 
ditions had  not  reached  the  point  where  they  were  clinically 
recognizable.  There  is  much  reason  to  suspect  that  it  is  very 
large. 

The  experimental  data  presented  in  this  chapter,  leave  no  room 
for  doubt  that  scurvy  is  a  deficiency  disease  resulting  from  the 
lack  of  a  specific  chemical  substance  in  the  food.  This  sub- 
stance is  not  essential  in  all  mammals,  but  is  indispensable  to 
man,  monkey  and  guinea  pig,  and  apparently  also  to  swine  and 
many  other  species  (51).  It  has  been  shown,  however,  that  the 
rat  and  perhaps  the  prairie  dog  (22)  possess  the 'power  to  syn- 
thesize this  substance,  and  are  accordingly  immune  to  this  "defi- 
ciency" disease. 

212.  Scurvy  Among  Infants  Is  Due  to  Unnatural  Feeding 
and  is  Relatively  New. — It  is  interesting,  in  the  light  of  the 
large  amount  of  accumulated  knowledge  of  the  etiological  factor 
in  scurvy,  which  the  last  few  years  has  brought  forth,  to  cor- 
relate the  history  of  human  scurvy  with  the  changed  conditions 
under  which  large  groups  of  persons  have  lived  at  different  times. 
In  very  early  times  the  disease  attacked  chiefly  soldiers  and  pris- 
oners since  these  were  subjected  for  considerable  periods  to  sim- 
ple and  monotonous  diets  consisting  of  dry,  cooked  or  stale  foods, 
chiefly  cereal  grains  and  legume  seeds.  These  foods  possess  high 


194     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

keeping  qualities,  and  are  most  attractive  to  those  who  purvey 
for  large  masses  of  people,  especially  when  transportation  or 
storage  is  an  important  item  for  consideration. 

The  sailors  did  not  have  scurvy  until  the  days  of  long  voyages 
following  the  discovery  of  America.  In  these  voyages  they  were 
isolated  from  fresh  foods  for  weeks  or  months.  With  the  advent 
of  steam  navigation  no  special  precautions  have  been  found 
necessary  for  the  protection  of  sea-faring  men  against  this  dis- 
ease, for  they  frequently  have  access  to  fresh  food. 

Infantile  scurvy  is  not  often  mentioned  in  early  medical  writ- 
ings. It  was  not  until  about  the  middle  of  the  nineteenth  cen- 
tury that  it  began  to  attract  the  attention  of  medical  observers. 
The  cause  of  this  appears  clear.  Infants  were  until  the  last  few 
decades  either  nursed  or  invariably  lost.  The  methods  of  feed- 
ing infants  that  could  not  be  nursed  were  so  crude  and  unsatis- 
factory that  success  in  the  rearing  of  them  was  rare.  Not  until 
the  eighteenth  century  was  artificial  feeding  or  mixed  feeding 
mentioned  in  medical  literature.  Bread  and  water,  called 
"water  pap";  bread  and  pulse;  small  beer  with  egg,  etc.,  were 
the  common  foods  administered  to  an  infant  which  had  lost  its 
mother.  Usually  the  unfortunate  one  died  from  intestinal  infec- 
tion or  inanition  before  it  had  time  to  develop  scurvy. 

In  1894  Barlow  first  described  a  diseased  condition  which  we 
now  know  to  be  a  complication  of  rickets  with  scurvy  in  infants, 
and  the  syndrome  became  known  by  his  name.  He  states  that 
the  disease  was  new  in  England,  but  more  common  in  Germany, 
and  that  it  appeared  to  be  on  the  increase  both  in  England  and 
America.  This  paper  is  the  earliest  and  best  description  of 
scurvy  in  infants,  and  is  one  of  the  classics  of  medical  literature. 

213.  Relation  of  Pasteurization  of  City  Milk  Supplies  to 
Incidence  of  Infantile  Scurvy. — Underwood,  in  1793,  was  the 
first  to  use  cow's  milk  as  a  food  for  infants  in  his  practice  as  a 
midwife  (52).  About  the  middle  of  the  nineteenth  century  the 
manufacture  and  sale  of  proprietary  foods  began  to  prosper 
and  with  this  business,  doubtless  there  was  a  pronounced  in- 
crease in  infantile  scurvy.  The  development  of  the  science  of 
bacteriology  led  to  the  discovery  that  typhoid  fever,  bovine 
tuberculosis,  scarlet  fever,  septic  sore  throat  and  other  diseases 
might  be  borne  by  milk,  and  city  health  officers  began  a  cam- 
paign for  the  pasteurization  of  the  milk  supplies  of  cities.  While 
this  practice  protected  the  adult  members  of  the  population 
against  the  epidemics  which  had  been  shown  to  follow  milk 


THE  DIETARY  DEFICIENCY  DISEASES          195 

routes,  it  was  a  calamity  to  a  large  part  of  the  infant  life  of 
cities.  Milk  which  was  pasteurized  was  deficient  in  the  anti- 
scorbutic substance,  and  the  incidence  of  scurvy  among  infants 
tended  to  increase  as  the  artificial  feeding  of  infants  came  more 
and  more  into  vogue.  Only  through  the  researches  of  the  last 
decade,  has  this  danger  to  infants  become  fully  understood,  and 
the  means  of  correcting  this  tragic  error  discovered.  In  this 
phase  of  nutrition  investigation,  we  have  another  example  of 
animal  experimentation  contributing  a  great  blessing  upon  the 
human  race,  for  without  the  guinea  pig,  and  systematic  experi- 
mental studies,  years  or  decades  would  certainly  have  passed 
away  before  the  amount  of  progress  which  has  been  attained 
even  during  the  past  five  years  could  have  been  achieved. 
Thenceforward  we  may  confidently  look  for  the  protection  of 
babies,  soldiers,  explorers,  and  prisoners,  as  well  as  the  general 
population,  against  this  distressing  malady. 


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37.  Harden,  A.,  and  Robison,  R. :   Anti-scorbutic  properties  of  concentrated 

fruit  juices,  Biochem.  Jour.,  1920,  xiv,  171. 
Harden,  and  Robison:     Anti-scorbutic  properties  of  concentrated  fruit 

juices,  Jour.  Royal  Army  Corps,  1919,  January. 
Lewis,  H.  B.:     The  anti-scorbutic  value  of  the  banana,  Jour.  Biol. 

Chem.,  1919,  xl,  91. 
Delf :   Effect  of  heat  on  the  anti-scorbutic  accessory  factor  of  vegetables 

and  fruit  juices,  Biochem.  Jour.,  1920,  xiv,  211. 

38.  Zilva:     The  action  of  ultraviolet  rays  on  the  accessory  food  factors, 

Biochem.  Jour.,  1919,  xiii,  164. 

39.  Dutcher,  R.  A.,  Pierson,  E.  M.,  and  Biester,  A.:     The  anti-scorbutic 

properties  of  raw  lean  beef,  Science,  1919,  1,  184.    August  22. 

40.  Givens,   and   McClugage:      An   experimental   study   of  raw  and   dry 

potatoes,  Jour.  Biol.  Chem.,  1920,  xiii,  491. 

41.  McCollum,   Simmonds,   and  Pitz:      The   relation   of  the   unidentified 

dietary  factors,  the  fat-soluble  A  and  water-soluble  B  of  the  diet 
to  the  growth-promoting  properties  of  the  milk,  Jour.  Biol.  Chem., 
1916,  xxvii,  33. 

McCollum,  and  Simmonds:     The  nursing  mother  as  a  factor  of  safety 
in  the  nutrition  of  the  young,  Amer.  Jour.  PhysioL,  1918,  xlvi,  275. 

42.  Barnes,  R.  E.,  and  Hume,  E.  M.:     A  comparison  between  the  anti- 

scorbutic properties  of  fresh  heated  and  dried  cow's  milk,  Lancet, 
1919,  August  23. 

43.  Dutcher,  Pierson,  and  Biester:     The  anti-scorbutic  properties  of  raw 

beef,  Jour.  Biol.  Chem.,  1920,  xiii,  301. 

44.  Hart,  E.  B.,  Steenbock,  H.,  and  Ellis,  N.  R.:     Influence  of  the  diet 

on  the  anti-scorbutic  potency  of  milk,  Jour.  Biol.  Chem.,  1920,  xiii, 
383. 


198      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

45.  Butcher,   R.   A.,    Eccles,   C.   H.,   Dahle,    C.   D.,    Mead,    S.   W.,   and 

Schaefer,  O.  G.:  The  influence  of  diet  of  the  cow  on  the  nutritive 
and  anti-scorbutic  properties  of  cow's  milk,  Jour.  Biol.  Chem., 
1920-21,  xlv,  119. 

Hess,  A.  F.,  linger,  L.  J.,  Supplee,  G.  C.:  Relation  of  fodder  to  the 
anti-scorbutic  potency  of  salt  content  of  milk,  Jour.  Biol.  Chem., 
1920-21,  xlv,  229. 

46.  Hess,  and  Unger:     Factors  affecting  the  anti-scorbutic  value  of  foods, 

Amer.  Jour.  Dis.  Child.,  1919,  xvii,  221. 

47.  Anderson,  E.  V.,  Butcher,  R.  A.,  Eccles,  C.  H.,  and  Wilbur,  J.  W.: 

The  influence  of  heat  and  oxidation  upon  the  nutritive  and  anti- 
scorbutic properties  of  cow's  milk,  Science,  1921,  liii,  446,  May  6. 
Butcher,  R.  A.,  Harshaw,  H.  M.,  and  Hall,  J.  S.:   Vitamine  studies  viii. 
The  effects  of  heat  and  oxidation  upon  the  anti-scorbutic  vitamine, 
Jour.  Biol.  Chem.,  1921,  xlvii.  483. 

48.  Hess,  and  Unger:    The  destructive  effect  of  oxidation  on  anti-scorbutic 

vitamine,  Proc.  Soc.  Exp.  Biol.  and  Med.,  1921,  xviii,  143. 

49.  Hart,  Steenbock,   and  Smith:     Effect   of  heat   on  the  anti-scorbutic 

properties  of  some  milk  products,  Jour.  Biol.  Chem.,  1919, 
xxxviii,  305. 

Ellis,  Steenbock,  and  Hart:  Some  observations  on  the  stability  of 
the  anti-scorbutic  vitamine  and  its  behavior  to  various  treatments, 
Jour.  Biol.  Chem.,  1921,  xlvi,  367. 

McClendon,  J.  F.,  Bowers,  W.  S.,  and  Sedgwick,  J.  P.:  The  anti-scor- 
butic properties  of  commercially  dried  orange  juice,  Proc.  Soc.  Exp. 
Biol.  Chemists,  1921,  xlvi,  p.  ix. 

50.  American  Pediatric  Society  Investigations:  Arch.  Pediat.,  1898,  xv,  481. 

51.  Plimmer,  R.  H.  A.:     Note  on  scurvy  in  guinea  pigs,  Biochem.  Jour., 

1920,  xiv,  570. 

52.  Underwood,  M.:    A  treatise  on  the  diseases  of  children  with  directions 

for  the  management  of  infants  from  birth,  1793,  London. 
Barlow,  Thomas:    Infantile  scurvy  and  its  relation  to  rickets,  Lancet, 
1894,  i,  1075,  Nov.  10. 


FIG.  10. — Shows  edema  in  a  baby  fed  too  largely  on  skim 
milk  and  cereal  foods.  This  condition  is  frequently  asso- 
ciated with  incipient  ophthalmia  of  dietary  origin. — Cour- 
tesy of  Dr.  Bloch. 


FIG.  9. — Illustrates  the  appearance  of  a  young  prairie  dog  born  of  animals  brought 
from  New  Mexico.  After  weaning  time  it  lived  entirely  upon  a  diet  which  would  produce 
severe  scurvy  in  a  guinea  pig  in  fifteen  to  thirty  days  and  death  within  a  short  time 
thereafter.  It  grew  in  what  appeared  to  be  a  normal  manner,  and  presented  the  appear- 
ance of  perfect  health,  was  playful  and  extremely  fond  of  attention  from  those  in  the 
laboratory.  It  showed  no  evidence  of  developing  scurvy  while  growing  rapidly  during 
over  six  months  and  during  two  succeeding  months  when  he  did  not  grow. 


CHAPTER  IX 

THE  DIETARY  DEFICIENCY  DISEASES  (Continued) 
Beri-beri  and  Polyneuritis 

214.  The  Antiquity  of  Beri-Beri. — Beri-beri  is  a  disease  of 
great  antiquity,  which  was  for  a  long  time  confined  to  Japan,  the 
Dutch  East  Indies,  Malay  Peninsula,  Philippine  Islands,  India 
and  Southern  China.     It  was  at  one  time  believed  to  be  a  tropi- 
cal disease,  but  this  view  has  been  disproved  by  its  frequent  oc- 
currence in  recent  times  in  certain  other  localities,  especially  in 
the   subarctic   regions,   notably   Newfoundland,    Labrador   and 
Norway.    It  results  from  faulty  nutrition  and  will  occur  in  any 
part  of  the  world  if  man  restricts  his  diet  to  certain  articles  of 
food.    In  1914  there  was  an  outbreak  of  typical  beri-beri  in  the 
jail  at  Elizabeth,  New  Jersey,  caused  by  the  poor  diet  of  the 
inmates  (1). 

215.  Symptoms  of  Beri-Beri. — Beri-beri  is  a  form  of  periph- 
eral neuritis,  the  nerves  of  motion  and  sensation  being  chiefly 
affected.     It  occurs  in  two  distinct  forms,  the  wet  and  the  dry. 
Its  incipiency  is  manifested  by  fatigue  and  depression,  numb- 
ness and  stiffness  of  the  legs,  and  more  or  less  edema  of  the 
ankles   and   face.     In  the   dry   type,   wasting,   anesthesia   and 
paralysis  are  the  chief  manifestations.    The  most  marked  symp- 
tom in  the  wet  type  is  edema,  which  is  sometimes  excessive,  af- 
fecting the  trunk,  limbs  and  extremities.     In  both  forms  there 
is  generally  tenderness  of  the  calf  muscles  and  a  tingling  or 
burning  sensation  in  the  feet,  legs  and  arms.    The  mortality  in 
this  disease  is  usually  high. 

216.  Theories  as  to   the  Etiology  of  Beri-Beri. — Various 
theories  have  been  advanced  to  explain  its  etiology.    Since  pol- 
ished rice  is  very  poor  in  protein,  fat  and  phosphorus,  the  preva- 
lence of  beri-beri  among  rice-eating  peoples  was  by  some  attrib- 
uted to  the  low  protein  content  of  the  diet,  by  others  to  fat  star- 
vation, to  starvation  for  organic  forms  of  phosphorus,  or  to  in- 
toxication caused  by  a  poison  present  in  rice  stored  under  unfav- 
orable conditions.   Climate,  arsenical  poisoning  and  specific  in- 

199 


200     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

fection  were  likewise  proposed  as  factors  in  the  etiology  of  the 
disease.  It  was  impossible  to  determine  the  true  cause  of  beri- 
beri until  after  it  had  been  experimentally  produced  in  animals 
subsisting  on  an  inadequate  diet.  It  is  now  generally  accepted 
that  the  disease  is  the  sequel  to  specific  starvation  for  a  substance 
of  unknown  chemical  nature,  but  a  very  small  amount  of  which 
is  necessary  in  the  diet.  This  is  variously  designated  as  the  anti- 
neuritic  substance,  anti-beri-beri  vitamin,  water-soluble  B,  etc. 
Beri-beri  is,  therefore,  like  scurvy,  a  dietary  deficiency  disease, 
due  to  lack  in  the  food  of  a  specific  substance.  The  history  of  the 
study  of  this  disease  by  various  investigators  forms  in  preventive 
medicine  a  chapter  of  absorbing  interest. 

217.  The  Remarkable  Study  of  Human  Beri-Beri  by 
Kanehiro. — The  most  notable  among  the  early  investigations  re- 
lating to  the  etiology  of  beri-beri  is  the  work  of  Takagi  Kanehiro, 
Director-General  of  the  Japanese  navy.  About  the  year  1880 
the  disease  became  a  scourge  among  Japanese  sailors.  Between 
1878  and  1883  the  average  number  of  cases  treated  medically  in 
the  navy  was  323.5  per  1,000  per  year.  The  incidence  of  beri- 
beri during  these  years  average  annually  324  per  1,000  men. 

During  this  period  the  diet  of  the  sailors  consisted  of  polished 
rice  and  fish  as  the  principal  components,  the  remainder  being 
derived  from  a  number  of  vegetables.  Takagi,  suspected,  as  the 
result  of  a  visit  to  Europe,  during  which  he  was  impressed  with 
the  differences  in  the  diet  and  in  the  health  of  the  British  sailors 
as  compared  with  those  of  Japan,  that  beri-beri  might  be  due  to 
faulty  food.  He,  therefore,  commissioned  a  training  ship  to  make 
a  nine  months'  cruise  on  which  the  diet  of  the  common  sailors 
included  91  grams  of  protein  per  day.  The  better  fed  officers 
did  not  suffer  from  the  disease,  whereas  the  men  were  sorely  af- 
flicted. There  were  169  cases  of  beri-beri  among  276  men  during 
this  cruise. 

Another  ship  was  then  commissioned  to  make  a  similar  voyage 
with  the  protein  content  of  the  diet  for  the  common  sailors  raised 
to  155  grams  per  man  per  day.  There  was  almost  no  illness  dur- 
ing the  second  voyage,  as  contrasted  with  a  frightful  incidence 
of  beri-beri  on  the  first.  Among  the  crew  of  276  men  there  were 
but  14  cases  of  beri-beri.  This  experience  led  to  a  marked  im- 
provement of  the  diets  of  the  personnel  of  the  navy,  and  the  dis- 
appearance of  beri-beri  from  the  service.  The  improvement  was 
due  to  the  addition  of  more  meat  and  vegetables,  a  reduction  of 
the  amount  of  rice,  substituting  in  part  wheat  or  barley.  A 


THE  DIETARY  DEFICIENCY  DISEASES          201 

pint  and  a  quarter  of  milk  a  day  was  also  furnished  each  man. 
This  was  made  possible  through  the  employment  of  condensed 
milk.  The  successful  condensation  of  milk  on  a  commercial 
scale  began  in  England  in  1856.  As  a  result  of  these  changes  in 
the  diet,  beri-beri  became  very  rare.  Diseases  of  the  digestive 
tract  and  of  the  respiratory  system  became  less  prevalent  and 
diseases  of  the  eyes  were  diminished  to  one  half  the  former  in- 
cidence (2) .  The  Japanese  officials  were  of  the  opinion  that  the 
increased  meat  consumption  was  responsible  for  the  protection 
against  beri-beri. 

For  many  years  this  experience  of  the  Japanese  navy  was  re- 
garded as  a  demonstration  of  the  importance  of  a  protein  rich 
diet.  That  this  was  not  the  true  explanation  of  the  cause  of  the 
immunity  of  the  Japanese  sailors  to  beri-beri,  is  clear  from  the 
history  of  the  disease  among  the  crews  of  Norwegian  vessels.  In 
the  invigorating  climate  of  the  northern  seas,  beri-beri  suddenly 
became  common  among  the  Norwegian  sailors  after  1894, 
whereas  before  that  time  it  had  been  quite  unknown.  Before 
1894  the  diet  of  these  men  consisted  of  bread  made  from  rye  flour, 
milled  without  the  removal  of  the  germ,  peas  and  salted  meat 
mostly  fat  pork.  After  that  year  it  consisted  of  white  bread 
made  from  bolted  wheat  flour,  peas,  salt  pork  once  or  twice  a 
week,  preserved  meat  and  fish  three  or  four  times  a  week,  and 
dry  fish  once  a  week.  Here  was  a  case  in  which  the  addition  of 
meat  and  fish  in  liberal  amounts,  although  increasing  greatly 
the  protein  consumption,  was  nevertheless  followed  by  the  sud- 
den appearance  of  beri-beri,  a  new  disease  in  that  part  of  the 
world.  It  is  reported  that  one  sea  captain  refused  to  accept  the 
white  bread,  and  provided  for  his  own  table  a  supply  of  the 
customary  rye  flour  bread.  When  beri-beri  attacked  his  crew 
he  was  able  for  a  time  to  afford  his  men  relief  by  sharing  his 
brown  bread  with  them,  but  because  of  the  limited  supply  was 
forced,  finally,  to  deny  it  to  them  to  save  himself  (3).  These 
observations  show  clearly  that  meat  and  bread  in  abundance, 
together  with  some  peas,  does  not  constitute  a  satisfactory  diet. 
When  bread  is  made  of  bolted  flour,  and  is  used  as  the  main 
article  of  the  diet,  the  deficiency  of  the  latter  in  water-soluble  B 
will  be  sufficiently  pronounced  to  cause  beri-beri.  Muscle  meats 
and  fish  also  contain  very  little  of  this  protective  substance. 

218.  The  Classic  Experiment  of  Eijkman  on  the  Production 
of  Beri-Beri  in  Birds  by  Diet. — The  most  remarkable  observa- 
tion in  the  history  of  beri-beri,  and  the  one  which  inaugurated 


202      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

the  modern  era  of  investigations  in  the  field  of  nutrition  was 
made  in  1897  by  the  Dutch  physician,  Eijkman  (4).  This  in- 
vestigator was  medical  officer  to  a  prison  in  Java,  where  beri- 
beri was  common.  He  noticed  that  the  poultry  which  fed  upon 
the  garbage  of  the  hospital  showed  symptoms  of  paralysis  strik- 
ingly suggestive  of  those  of  his  patients,  and  died  with  extensive 
degeneration  of  the  peripheral  nerves.  Eijkman  was  led  by  this 
chance  observation  to  conduct  systematic  experiments  with 
chickens  and  pigeons.  He  fed  some  on  rice  in  the  natural  con- 
dition with  the  husk  attached  to  the  grain;  others  he  fed  on  rice 
from  which  the  husk  had  been  removed  but  which  still  retained 
the  outer  layer  or  "silverskin,"  and  the  embryo  or  germ;  still 
others  he  fed  on  rice  which  had  been  milled  and  polished. 

The  milling  of  rice  removes  the  bran  or  cellulose  membrane, 
together  with  the  aleurone  layer  and  the  germ.  The  coating  on 
our  polished  rice  is  talcum  powder.  Eijkman's  results  demon- 
strated definitely  that  rice  which  had  lost  its  "silverskin"  would 
produce  the  condition  of  nerve  degeneration  to  which  he  gave  the 
name  polyneuritis  gallinarum,  and  which  he  rightly  considered  to 
be  the  analogue  of  beri-beri  in  man. 

Eijkman  did  not  correctly  interpret  the  cause  of  the  production 
of  beri-beri  by  polished  rice  and  its  prevention  by  the  unpolished 
grain.  It  has  been  shown  by  others  that  the  substance  which 
protects  against  beri-beri,  and  which  is  absent  from  polished  rice, 
is  in  great  measure  concentrated  in  the  germ  of  the  seed.  This 
portion  is  situated  in  an  exposed  position  at  the  tip  of  the  ker- 
nel, and  is  easily  rubbed  off  in  milling.  On  the  grain  of  polished 
rice,  there  is  a  tiny  pit  in  which  the  germ  rested  before  its  re- 
moval. 

Eijkman's  interpretation  of  the  experiments  was  that  the  "sil- 
verskin" of  the  rice  kernel  contained  some  substance  which  neu- 
tralized the  injurious  influence  of  the  starch-rich  diet.  To  quote: 
"Aus  den  diesbeziiglichen  Versuchen  zog  ich  den  Schluss,  dass 
in  den  Silberhautchen  wahrscheinlich  ein  Stoff  oder  Stoffe  vor- 
handen  sind,  wodurch  der  schadigende  Einfluss  der  starkehaltigen 
Nahrung  neutralisert  wird"  (4) . 

219.  Climate  Not  a  Factor  in  the  Production  of  Beri-Beri. 
— He  also  studied  the  influence  of  climate  as  a  factor  in  the 
etiology  of  the  disease,  but  found  it  a  negligible  factor.  In  the 
large  cities  of  the  East  Indies  (Batavia,  Soeralaja),  66.7  per  cent 
of  the  people  suffered  from  beri-beri,  as  against  30.9  per  cent 
among  mountain  dwellers.  The  greater  number  of  the  first  group 


THE  DIETARY  DEFICIENCY  DISEASES          203 

ate  milled  rice.  Prisoners  fed  principally  on  milled  rice  showed 
an  incidence  of  80  per  cent  near  the  sea,  as  compared  with  62  per 
cent  in  the  mountains.  In  one  prison  5.8  per  cent  of  the  in- 
mates suffered  from  beri-beri  when  supplied  with  polished  rice, 
but  the  disease  disappeared  when  unmilled  rice  was  substi- 
tuted (5). 

220.  Other   Foods  Than    Rice   May   Induce   Beri-Beri. — 
Eijkman  tested  the  hypothesis  that  a  high  starch  content  in  the 
diet  predisposed  to  the  disease.     He  produced  polyneuritis  in 
birds  by  restricting  their  diets  to  various  Indian  starches  (Am- 
bon-sago, pearl-tapioca,  sago,  etc.),  and  found  that  the  typical 
symptoms  were  produced.    These  experiments  were  confirmed 
and  extended  by  Grijns   (6),  Schaumann   (7),  and  Hoist   (3). 
They  showed  that  in  addition  to  polished  rice,  milled  barley, 
milled  wheat,  and  bread  made  from  bolted  flour,  tapioca,  etc., 
produced  the  disease  in  birds. 

221.  Schaumann's  Studies  on  the  Etiology  of  Beri-Beri. — 
Schaumann  further  demonstrated  that  dried  codfish  and  pickled 
meats,  heated  for  a  time  in  an  autoclave  at  120°  C.  would  pro- 
duce polyneuritis  when  the  energy  requirements  of  his  animals 
were  covered  by  these  foods.    He  was  the  first  to  employ  mam- 
mals in  studies  relating  to  polyneuritis.    Dogs,  cats,  rats,  a  goat 
and  an  ape  were  used  in  his  experiments  (8).     He  produced  the 
characteristic  symptoms  of  the  disease  in  all  these  animals,  but 
not  in  mice.    The  latter,  however,  suffered  loss  of  weight  and 
presented  signs  of  malnutrition. 

222.  The  Germ  of  the  Rice  Kernel  Is  Richest  in  the  Anti- 
Beri-Beri  Substance. — In  none  of  these  early  experiments  was 
the  importance  of  the  germ  or  embryo  of  the  seeds  recognized 
as  of  special  importance.    The  cortical  layer  was  regarded  as 
the  part  producing  the  favorable  results.    McCollum  and  Davis 
(9)  in  their  study  of  the  wheat  kernel  were  the  first  to  call  atten- 
tion to  the  fact  that  the  germ  is  exceedingly  rich  in  the  substance 
which  is  curative  for  polyneuritis.    They  suggested  that  it  is  the 
loss  of  the  germ  of  the  rice  kernel  rather  than  the  cortical  layer 
which  robs  the  seed  of  its  protective  power  against  beri-beri. 

These  experiments  of  Eijkman,  Grijns,  Hoist  and  Schaumann 
established  the  fact  that  the  feeding  of  milled  products  of  the 
cereals  caused  the  degeneration  of  the  peripheral  nerves  charac- 
teristic of  beri-beri.  They  did  not  make  clear  the  cause  of  this 
degeneration.  It  has  been  mentioned  that  Eijkman  believed 
that  there  was  a  detoxicating  effect  of  the  "silverskin"  for  the 


204     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

injurious  effects  of  the  endosperm  of  the  rice  or  other  cereal. 
Schaumann  (10)  examined  the  hypothesis  that  food-stuffs  caus- 
ing beri-beri  contain  a  toxic  substance  or  substances  which  pro- 
duce the  disease.  He  was  unable  to  detect  any  poison  which 
might  have  been  produced  as  a  metabolic  product  by  a  microbe. 
He  tested  polished  rice  for  acetone,  aceto-acetic  acid,  oxalic  acid 
and  oxy butyric  acid  with  negative  results.  He  found  the  urine 
of  patients  did  not  contain  a  toxin,  and  offered  the  explanation 
that  beri-beri  was  due  to  starvation  for  certain  organic  phos- 
phorus compounds  which  were  removed  during  the  milling 
process. 

223.  Other  Views  Relating  to  the  Cause  of  Beri-Beri. — In 
1899  Laurent  (11)  attributed  beri-beri  to  lack  of  sufficient  fat 
in  the  diet.     He  believed  this  type  of  specific  starvation  caused 
a  lowering  of  the  vitality  and  made  the  subjects  susceptible  to 
an  infection  which  was  the  specific  cause  of  the  disease.     He 
attributed  the  beneficial  effects  of  the  addition  of  meat  to  the 
diet  of  the  Japanese  sailors,  to  the  increase  in  the  fat  content  in 
the  food. 

Montgomery  Smith  (12)  supported  the  infection  hypothesis. 
He  cited  the  ship  Lodestar  as  having  a  bad  reputation  for  beri- 
beri outbreaks.  A  Japanese  revenue  cruiser  had  new  cases  of 
beri-beri  during  successive  years  while  the  southwest  monsoon 
blew. 

224.  Sir  Patrick  Manson's  Conclusions  Regarding  the  Cause 
of  Beri-Beri. — Manson  (13)  deduced  from  all  the  evidence  which 
he  had  accumulated,  the  theory  that  the  disease  was  due  to  a 
toxin  elaborated  by  a  germ  growing  outside  the  body.    He  sug- 
gested that  improper  handling  of  rice  led  to  its  infection  and 
the  development  of  the  toxin.    He  was  opposed  to  the  theory 
that  meat  in  the  diet  was  a  protection  against  the  disease,  and 
cited  the  experience  of  the  Singapore  jail,  where  in  1898-99,  there 
was  an  ordinary  and  a  penal  diet.    The  former  was  a  liberal  one 
of  wheat  flour  and  fresh  meat.    The  penal  diet  contained  no 
meat.    The  greater  number  of  cases  of  beri-beri  occurred  among 
those  inmates  of  the  prison  having  meat  in  their  diet.     McLeod 
(cited  by  Manson)  mentions  a  case  where  beri-beri  attacked  the 
officers  on  shipboard,  but  not  the  common  sailors.    The  former 
had  such  luxuries  as  haddies,  clams,  oysters,  lobster  and  salmon. 
It  was  argued  that  lack  of  protein  could  not  be  the  cause  of  the 
outbreak. 

Manson  also  cited  the  observation  of  Hirota,  who  witnessed 


THE  DIETARY  DEFICIENCY  DISEASES          205 

52  instances  of  the  development  of  the  disease  in  nursing  infants 
whose  mothers  were  suffering  from  beri-beri.  When  these  in- 
fants were  weaned  and  fed  condensed  or  fresh  milk  they  recov- 
ered promptly,  whereas  five  not  so  treated  died.  It  was  argued 
by  Manson  that  a  child  acquiring  a  germ  disease  from  the  mother 
will  not  recover  so  rapidly,  but  that  one  intoxicated  by  taking 
poisonous  milk  would  be  expected  to  do  so.  This  was  inter- 
preted by  Manson  as  supporting  his  theory  of  intoxication. 

225.  Arsenic  Suggested  as  the  Agent  Producing  Beri-Beri. 
—Mention  should  also  be  made  of  the  view  of  Sir  Ronald  Ross, 
who  believed  that  beri-beri  was  due  to  arsenical  poisoning  (14). 
Symptoms  of  peripheral  neuritis  have  been  observed  in  persons 
who  drank  beer  containing  arsenic. 

The  view  that  beri-beri  was  due  to  lack  of  sufficient  phos- 
phorus in  the  diet  was  supported  by  Edie  and  Simpson  (15). 
Polished  rice  and  cereal  foods  prepared  from  the  endosperm  of 
the  grains  contain  very  little  phosphorus,  and  suggested  the  phos- 
phorus starvation  theory.  In  the  light  of  later  experimental 
studies,  these  seemingly  irreconcilable  observations  have  been 
made  clear. 

226.  Fletcher's    Studies    on    Human    Beri-Beri. — The    re- 
searches of  Eijkman,  of  Schaumann,  and  of  Grijns  led  Fletcher 
(16),  a  physician  in  the  Kuala  Lumpur  Lunatic  Asylum  in  the 
Federated  Malay  States,  to  carry  out  a  thorough  experiment  on 
human  subjects,  with  the  object  of  determining  the  relation  of 
rice  to  beri-beri.    Fletcher  divided  the  hospital  into  two  sections, 
each  containing  nearly  equal  numbers  of  patients.    To  one  group 
he  supplied  milled  rice,  and  to  the  other  "cured"  rice.    "Cured" 
rice  was  prepared  by  soaking  unhusked  kernels,  or  paddy,  for 
12-24  hours  in  water,  then  heating  the  soaked  grains  over  a  slow 
fire  until  they  burst.    The  rice  was  then  spread  to  dry  in  the 
sun.     Such  rice  is  easily  husked  and  is  ground  for  use  without 
polishing.    The  entire  kernel,  including  the  germ,  was  therefore 
supplied  to  half  the  patients.    The  diet  of  all  the  inmates  of  the 
asylum  consisted  of  four  ounces  of  fresh  meat  four  times  a  week ; 
five  and  one-third  ounces  of  fresh  fish  twice  a  week;  five  and 
one-third  ounces  of  salt  fish  once  a  week;  eight  ounces  of  vege- 
tables daily;  one  and  one-third  ounces  of  curry  stuffs  daily; 
two-thirds  ounce  of  cocoanut  oil  daily,  and  thirty-eight  ounces  of 
uncooked  rice  daily.     Since  rice  absorbs  about  three  times  its 
weight  of  water  on  cooking,  and  becomes  very  bulky,  it  seems 
incredible  that  so  large  an  amount  of  rice  could  be  eaten  by  man. 


206      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

The  only  difference  in  the  diets  of  the  two  groups  of  patients  was 
in  the  character  of  the  rice. 

The  diets  were  continued  unchanged  throughout  a  year  with 
the  following  results:  The  group  eating  the  milled  rice  developed 
a  large  number  of  cases  of  beri-beri,  whereas  no  cases  developed 
in  the  group  fed  the  steamed  rice  which  contained  all  parts  of 
the  kernel.  Fletcher  rearranged  the  patients  and  mingled  some 
of  the  beri-beri  patients  with  the  well,  and  continued  the  experi- 
ment. The  result  was  a  complete  demonstration  that  the  dis- 
ease was  due  to  the  consumption  of  a  diet  consisting  in  great 
measure  of  meat,  fish  and  milled  rice.  We  now  know  that  the 
same  result  will  follow  the  too  free  use  of  the  endosperm  of  any 
of  the  cereal  grains  as  food. 

It  has  been  found  by  experiments  on  man  and  animal,  that 
the  germ  of  rice  is  especially  rich  in  the  protective  substance, 
water-soluble  B,  a  lack  of  which  leads  to  the  development  of 
beri-beri.  The  diet  of  the  asylum  patients  observed  by  Fletcher 
contained  a  sufficient  amount  of  this  substance  when  the  entire 
grain  was  its  chief  component,  but  not  when  the  milled  rice  was 
used.  The  diet  of  the  institution  cannot  be  regarded  as  satis- 
factory for  the  promotion  of  health  over  a  long  period  of  time 
even  when  the  steamed  rice  was  employed,  but  it  was  then  suffi- 
ciently good  to  prevent  the  development  of  beri-beri.  The  eight 
ounces  of  vegetables,  the  nature  of  which  were  not  specified,  suf- 
ficed to  furnish  enough  anti-scorbutic  substance  to  prevent 
scurvy.  This  diet,  principally  derived  from  rice,  meat,  and  fish 
would  not,  if  we  may  judge  from  the  vast  amount  of  experimental 
data  obtained  with  animals,  maintain  over  a  period  of  several 
years  normal  health  in  an  adult. 

227.  Many  Grades  of  Injury  Less  Severe  Than  the  Clin- 
ically Recognizable  Deficiency  Diseases. — The  tendency  of 
those  who  have  investigated  the  relation  of  the  diet  to  disease, 
as  in  the  experiments  under  discussion,  has  been  to  tacitly  as- 
sume that  a  diet  which  does  not  lead  to  clinically  recognizable 
symptoms  of  malnutrition  is  essentially  an  adequate  one.  The 
tendency  during  recent  years,  while  knowledge  of  the  properties 
of  foods  and  the  physiological  effects  of  faulty  diets  has  been 
rapidly  accumulating,  has  been  to  appreciate  the  existence  of 
many  grades  of  malnutrition.  It  is  becoming  more  and  more 
evident  that  even  slight  departure  from  the  optimal  in  the  com- 
position of  the  food,  may  lead  to  states  of  nutritional  instability 
which  become  contributing  factors  to  physical  breakdown  when 


THE  DIETARY  DEFICIENCY  DISEASES          207 

hygienic  factors  are  unfavorable,  or  when  infectious  processes 
are  operating.  Even  under  the  most  favorable  living  conditions, 
however,  there  can  be  little  doubt  that  under  such  circumstances 
the  body  tissues  lose  their  vitality  and  the  span  of  life  tends  to 
shorten. 

228.  Further  Investigations  by  Schaumann. — After  Eijk- 
man's  discovery  that  polyneuritis  could  be  induced  in  birds  on  a 
subsistence  of  milled  rice,  Schaumann,  in  the  next  few  years, 
showed  that  pressed  yeast,  wheat  bran  and  dried  testicle  of  the 
bull,  were  all  capable  when  added  to  such  a  diet  of  protecting 
animals  against  the  disease.  Other  observers  added  beans,  egg 
yolk,  beef  heart,  etc.,  to  the  list  of  foods  protective  against  beri- 
beri. Eijkman  used  a  water  or  hydrochloric  acid  extract  of 
rice  polish,  and  found  it  effective.  Schaumann  supplemented 
milled  rice  with  purified  protein  and  with  mineral  salts,  but  found 
that  these  additions  did  not  prevent  the  development  of  the  dis- 
ease. These  observations,  together  with  the  failure  of  inorganic 
phosphates  to  protect  against  beri-beri,  confirmed  his  belief  that 
there  was  a  protective  substance  in  certain  foods  to  which  he 
gave  the  name  "activator."  He  began  to  correlate  the  high  con- 
tent of  organic  forms  of  phosphorus  in  rice  polish  with  its  cura- 
tive power.  The  disease  was,  he  believed,  a  specific  starvation 
for  this  "activator,"  which  he  believed  to  be  an  organic  com- 
pound of  phosphorus.  This  view  was  recognized  by  the  Far 
Eastern  Association  of  Tropical  Medicine.  They  adopted  a 
resolution  that  rice  containing  less  than  0.4  per  cent  of  phos- 
phorus should  be  excluded  by  law  from  those  countries  in  which 
this  cereal  formed  the  principal  food  grain.  The  view  that  a  lack 
of  certain  phosphorus-containing  substances  constituted  the  eti- 
ological  factor  in  beri-beri  was,  however,  soon  to  be  abandoned. 

It  is  easy  now  as  we  look  back  upon  the  efforts  of  various  in- 
vestigators to  account  for  the  etiology  of  beri-beri,  to  under- 
stand how  so  many  different  views  as  to  its  cause  could  arise. 
The  observations  were  in  themselves  generally  reliable  but  it  was 
not  possible  to  interpret  them  because  nobody  understood  what 
factors  were  necessary  for  an  adequate  diet,  and  the  specific  role 
they  played.  The  existence  of  certain  food  substances  which  are 
needed  in-  but  small  amounts,  and  which  serve  some  purpose  other 
than  that  of  a  source  of  protein  or  energy,  while  hinted  at  by 
the  prevailing  views  on  scurvy,  and  by  one  or  two  students  of 
beri-beri  were  on  the  whole  practically  unappreciated.  The  re- 
corded speculation  regarding  them  partook  of  a  very  hazy  and 


208      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

nebulous  character.  The  experimental  demonstration  of  the 
existence  of  such  factors  by  crucial  experiments  on  animals  was 
a  matter  of  great  difficulty  as  has  already  been  pointed  out  in 
the  second  chapter.  The  history  of  beri-beri  serves  as  an  excel- 
lent example  of  the  inability  of  the  student  of  pathology  or  of 
epidemiology  to  solve  the  problem  of  the  etiology  of  such  a  dis- 
ease. It  illustrates  the  value  of  fundamental  chemical  research 
directed  toward  the  solution  of  the  problem  of  the  chemical  com- 
plexes which  can  serve  as  the  simplest  adequate  diet  for  the 
normal  nutrition  of  man  or  animal. 

Eijkman's  experimental  production  of  polyneuritis  in  birds, 
which  is  now  generally  accepted  as  the  analogue  of  beri-beri  in 
man,  failed  to  receive  for  a  decade,  the  attention  which  it  de- 
served. Finally,  however,  the  significance  of  his  studies  became 
appreciated  and  a  new  era  in  the  development  of  preventive 
medicine  dates  from  the  publication  of  his  paper  in  1897  (4). 

229.  Schaumann's  Designation  of  the  Anti-Beri-Beri  Sub- 
stance as  "Activator." — It  has  been  pointed  out  that  Schaumann 
in  1908,  sought  to  explain  the  etiology  of  beri-beri  on  the  basis 
of  specific  starvation  for  some  organic  phosphorus  compound. 
Further  studies  led  him  in  1912  to  the  isolation  from  rice  polish- 
ings  of  a  phosphorus-free  base  which  was  capable  of  curing  ex- 
perimental polyneuritis.    This  substance  he  called  "activator," 
and  assumed  that  its  action  was  of  an  enzymic  nature. 

230.  Funk's  Designation  of  the  Anti-Beri-Beri  Substance 
as  "Vitamine." — Funk  in  1912   (17)   showed  that  a  substance 
which  was  organic  and  of  a  basic  nature  could  be  isolated  from 
rice  bran  by   extraction  with   alcohol  containing  hydrochloric 
acid,  which   was  precipitable   by   phosphotungstic   acid,   silver 
nitrate  and  barium  hydroxid,  and  partially  by  mercuric  chlorid. 
This  caused  the  cure  of  polyneuritis  induced  in  birds  by  feeding 
them  polished  rice.    The  following  year  he  confirmed  this  ob- 
servation and  named  the  substance  "vitamine"  (18) .    In  the  same 
year  Chamberlain  and  Vedder  (20),  and  Edie,  Evans,  Moore, 
Simpson  and  Webster  (21)  confirmed  these  observations. 

231.  Suzuki's  Designation  of  the  Anti-Beri-Beri  Substance 
as  "Oryzanin." — Almost  simultaneously,  Suzuki,  Shimamura  and 
Odaki  (19)  reported  studies  almost  identical  with  those  of  Funk, 
and  fully  confirming  the  latter.    They  designated  the  substance 
which  they  isolated  from  rice  bran,  oryzanin.     It  thus  became 
established  that  beri-beri,  which  is  called  polyneuritis  when  it  is 
produced  experimentally  in  animals,  is  due  to  starvation  for  a 
specific  substance,  of  which  but  a  surprisingly  small  amount  is 


THE  DIETARY  DEFICIENCY  DISEASES          209 

necessary  to  prevent  the  nervous  symptoms  characteristic  of  the 
disease. 

232.  Kohlbrugge's   Conclusions   Regarding   the    Cause  of 
Beri-Beri. — Since  the  earlier  experiments  of  Schaumann,  there 
had  been  a  tendency  to  associate  beri-beri  with  scurvy  and  Bar- 
low's  disease.    Kohlbriigge    (22)    associated  the  occurrence  of 
these  diseases  with  an  unbalanced  diet  too  rich  in  starch.    He 
believed  such  a  diet  favored  the  growth  of  fermentative  bacteria 
which  formed  sufficient  acids  to  tend  to  self  sterilization  of  the 
intestine,   depressing   or   extinguishing  the   normal   flora.    He, 
therefore,  designated  them  "fermentation  diseases."    These  or- 
ganisms were  believed  to  occur  in  rice  and  other  cereals,  and 
were  regarded  as  perhaps  related  to  acetic  acid  formers.    It  was 
postulated  that  a  diet  containing  free  acids  tended  to  hold  the 
injurious  kinds  in  abeyance.     This  view  was  opposed  to  that  of 
Wright  (23),  who  had  in  1895  expressed  the  belief  that  scurvy 
was  caused  by  the  exclusive  use  of  foods  possessing  a  prepon- 
derance of  acid  elements  over  bases. 

233.  The  Year  1912  Saw  Great  Developments  in  Our  Un- 
derstanding of  the  Deficiency  Diseases. — It  was  in  1912,  that 
the  true  relation  of  the  diet  to  scurvy  was  brought  to  light. 
Hoist  and  Froelich  (24)  in  that  year  discovered  that  a  diet  of 
cereals  of  different  kinds  or  of  bread  caused  the  development  of 
scurvy  in  guinea  pigs,  whereas  a  diet  consisting  of  cabbage,  car- 
rots and  dandelion  did  not  cause  the  disease,  although  the  ani- 
mals lost  30  to  40  per  cent  in  weight.    The  latter  foods  were 
found  to  be  effective  when  administered  to  animals  suffering 
from  scurvy,  in  promptly  relieving  their  symptoms.    This,  they 
found,  could  be  done  only  with  raw  foods.    Either  cooked  or 
dried  cabbage,  for  example,  was  without  virtue  as  an  anti-scor- 
butic food.    It  seemed  that  in  the  course  of  cooking  or  drying 
something  essential  was  destroyed. 

234.  The  Discovery  of  Vitamins  Did  Not  Result  in  an  Un- 
derstanding of  Diet. — Even  after  these  discoveries  had  been 
made,  however,  no  one  was  able  to  define  in  chemical  terms  what 
constituted  an  adequate  diet.     It  was  beginning  to  be  appre- 
ciated   that    certain    substances — vitamin — anti-scorbutic    sub- 
stance— must  be  taken  into  account  in  the  planning  of  the  diet 
in  addition  to  the  long  recognized  dietary  essentials.    Yet  one, 
and  probably  two  organic  factors  which  are  indispensable  to 
normal  nutrition  in  man,  remained  to  be  discovered,  and  future 
experimental  studies  were  to  reveal  how  surprisingly  sensitive 
is  the  animal  body  to  nice  adjustments  among  certain  of  the 


210     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

inorganic  elements.  There  still  remained  to  learn  how  widely 
the  proteins  of  various  foods  differed  in  their  nutritive  values, 
and  there  still  remained  to  discover  the  exact  dietary  properties 
of  each  of  the  more  important  natural  food-stuffs,  which  should 
make  it  possible  to  combine  them  in  a  manner  suited  to  form  a 
diet  of  optimal  character. 

235.  There  Are  Two  Forms  of  Beri-Beri. — It  has  been  men- 
tioned that  beri-beri  occurs  in  two  forms,  the  wet  and  the  dry. 
Those  suffering  from  the  dry  type  are  usually  at  least  somewhat 
emaciated,  whereas  those  suffering  from  wet  beri-beri  are  in  a 
dropsical  condition.     Until  very  recently  there  was  no  clue  to 
the  cause  of  this  difference.     A  brief  history  of  the  observations 
leading  to  its  explanation  will  be  of  interest. 

236.  Epidemic  Dropsy,  War  Edema  and  Wet  Beri-Beri. — 
There  are  recorded  many  instances  of  the  occurrence  of  epidemics 
of  dropsy  during  times  of  food  shortage  owing  to  famine  condi- 
tions  brought  on   by   drought,   flood   devastation   or  war.     In 
1876-77  there  occurred  a  famine  in  India,  and  in  eight  famine 
districts  nine-tenths  of  all  deaths  were  due  to  famine  dropsy, 
dysentery,   diarrhea   and  debility    (25).    The  Government  at- 
tempted to  operate  a  system  of  rationing  the  sufferers  by  deter- 
mining their  calorific  needs  calculated   on  the  basis  of  body 
weight.     This  system  proved  a  failure  because  those  who  ap- 
pealed for  relief  were  found  to  be  either  emaciated  or  apparently 
very  fat.    These  latter  appeared  to  be  in  no  immediate  danger 
of  starvation,  and  yet  they  were  in  many  cases  in  immediate 
danger  of  death,  because  they  were  not  really  fat  but  dropsical. 
This  contrast  between  one  group  of  the  population  which  was 
nothing  but  skin  and  bones,  and  another  which  was  bloated  as 
a  result  of  dropsy,  occurred  in  persons  of  all  ages. 

In  1899  Patterson  (26)  described  cases  of  edema  among 
Chinese  starving  during  a  period  of  famine.  Weed  seeds  and 
greens  obtained  from  wild  plants  were  the  only  food,  and  Pat- 
terson, who  apparently  was  not  familiar  with  any  literature  on 
the  subject,  called  it  "greens  dropsy."  In  1917  the  City  of 
Mexico  was  under  military  rule  for  several  months  and  many 
cases  of  dropsy  developed  in  persons  of  all  ages.  These  people 
had  been  reduced  to  beets  and  spinach  as  almost  their  sole  food 
supply. 

An  epidemic  of  edema  among  infants  has  been  reported  from 
Germany  by  Wagner.  It  was  caused  by  feeding  modified  milk 
alone  or  modified  milk  with  cereal  (27).  Potter  (28)  described 
an  epidemic  of  dropsy  among  infants  restricted  for  a  time  to 


THE  DIETARY  DEFICIENCY  DISEASES          211 

barley  water,  which  was  very  low  in  protein,  inorganic  and 
fat  content.  Czerny  and  Keller  have  called  attention  to  a  con- 
dition which  they  speak  of  as  "Mehlnahrschaden"  literally,  a 
state  of  malnutrition  resulting  from  too  much  cereal  in  the  diet 
(29).  This  they  regarded  as  the  equivalent  of  saying  that  they 
had  a  diet  too  rich  in  carbohydrate,  too  low  in  protein  and  too 
low  in  fat.  There  are,  we  now  know,  serious  mineral  deficiencies, 
lack  of  fat-soluble  A,  water-soluble  B  and  water-soluble  C  in  all 
cereal  preparations,  especially  when  these  represent  essentially 
the  endosperm  of  the  seed. 

Nutritional  edema  has  been  many  times  reported  in  medical 
literature.  It  occurred  especially  during  time  of  war  and  scarcity 
of  food.  During  the  great  war  the  condition  became  known  as 
war  edema.  In  earlier  literature  it  was  called  by  various  names 
such  as  prison  dropsy,  hunger  swelling,  epidemic  dropsy,  defi- 
ciency edema,  etc. 

Hoist  (30)  states  that  many  cases  of  dropsy  occurred  during 
the  Crimean  war  when  there  was  an  epidemic  of  scurvy.  He 
states  that  dropsy  occurs  every  year  on  French  fishing  vessels  off 
the  coast  of  Newfoundland.  Edema  was  very  common  among 
prisoners  in  England  and  America  during  the  first  half  of  the 
nineteenth  century.  This  happened  before  prisoners  received  the 
humane  treatment  and  moderately  satisfactory  diet  now  gener- 
ally accorded  them.  It  was  recognized,  as  some  of  the  names 
indicate,  that  it  had  its  origin  in  faulty  nutrition. 

Budzynski  and  Chelchowski  (31)  described  one  hundred  and 
ten  cases  of  "hunger  swelling"  during  the  war  in  Poland.  These 
cases  resulted  from  lack  of  food.  It  was  pointed  out  that  the 
most  marked  characteristic  of  the  condition  was  an  edema  which 
resembled  wet  beri-beri. 

Edema  has  been,  as  the  cases  mentioned  illustrate,  frequently 
associated  with  other  deficiency  diseases,  especially  beri-beri  and 
scurvy.  The  histories  of  the  cases  recorded,  point  to  a  low  pro- 
tein dietary  as  the  condition  favoring  the  development  of  the 
disease.  Indeed,  there  is  convincing  experimental  data  that 
seems  to  prove  that  protein  starvation  is  the  essential  specific 
cause  of  the  condition,  but  it  appears  that  a  water-rich  diet 
poor  in  protein,  especially  promotes  the  development  of  edema. 
Maver  refers  to  the  occurrence  of  edema  in  horses  and  oxen  which 
work  about  sugar  factories,  and  subsist  for  a  time  upon  cane. 
Cattle  fed  distiller's  wash,  or  too  liberally  on  beet  pulp  become 
dropsical  (32). 

237.     Experimental  Production  of  Edema  Through  Protein 


212      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Starvation. — Denton  and  Kohman  (33)  have  conducted  experi- 
ments with  rats  which  seem  to  establish  the  fact  that  foods  poor 
in  protein  and  rich  in  water,  tend  to  cause  edema.  They  re- 
stricted young  rats  to  a  diet  of  carrots  and  found  that  a  large 
percentage  of  them  suffered  from  edema.  Kohman  (34)  ex- 
tended these  experiments  by  feeding  carrots  supplemented  in 
several  ways  with  purified  food  substances,  and  found  that  edema 
could  be  produced  only  in  the  animals  confined  to  an  inadequate 
protein  intake  and  given  somewhat  excessive  amounts  of  water 
with  their  food.  These  results  correspond  so  closely  with  human 
experience  and  with  the  conditions  under  which  a  dropsical  state 
occurs  in  domestic  animals  that  they  seem  to  establish  the  cause 
of  edema  in  times  of  war  and  famine. 

238.  Sequence  of  Events  as  Famine  Conditions  Approach. 
— On  the  approach  of  famine  conditions  due  to  drought  a  short- 
age of  forage  plants  ensues,  and  the  animals,  for  want  of  pas- 
turage are  killed  for  food  or  become  too  emaciated  to  be  of 
value  for  this  purpose,  and  finally  die.    Green  plants  fail  utterly, 
and  the  population  becomes  restricted  to  a  diet  of  cereals  and 
other  seeds.    Since  these  are  the  least  perishable  of  our  common 
food-stuffs,  they  form  the  last  reserve.    Especially  when  rice 
forms  the  principal  cereal  in  the  diet,  the  protein  content  is  very 
low.    This  is  the  grain  most  used  in  those  countries  where  peri- 
odic famines  occur,  as  in  India  and  China. 

When  famine  conditions  are  brought  about  by  war,  circum- 
stances may  be  very  different.  The  cereals  and  other  seed  grains 
used  as  human  food  are  at  a  premium  as  breadstuffs  and  meats 
become  scarce  and  dear,  since  a  large  part  of  the  population  are 
called  from  agriculture  to  the  army  or  to  war  industries.  The 
less  fortunate  of  the  civilian  population  come  to  subsist  more 
and  more  upon  such  low  protein  foods  as  potatoes  and  succulent 
vegetables,  together  with  a  limited  amount  of  cereal  and  little 
or  no  meat  or  milk.  It  is  under  these  conditions  that  nutritional 
dropsy  has  appeared  on  many  occasions. 

239.  Relation  Between  Wet  and  Dry  Beri-Beri. — It  will 
thus  be  seen  that  there  is  convincing  evidence  that  in  wet  beri- 
beri, protein  starvation  is  superimposed  upon  a  deficiency  of  the 
anti-neuritic  substance,  water-soluble  B.    Wet  beri-beri  is  a  con- 
dition resulting  from  a  double  deficiency,  whereas  uncomplicated 
dry  beri-beri  would  appear  to  be  due  to  a  single  deficiency.    This 
is,  doubtless  rarely  the  case,  however,  since  the  diet  is  so  poor 
in  quality  with  respect  to  several  factors,  wherever  beri-beri 


THE  DIETARY  DEFICIENCY  DISEASES          213 

occurs,  that  it  can  scarcely  be  regarded  as  a  specific  syndrome 
of  an  uncomplicated  nature.  It  is  this  fact  that  explains  the 
tendency  of  students  of  the  diseases  of  dietary  origin  to  em- 
phasize the  points  of  similarity  of  the  two  "deficiency"  diseases, 
scurvy  and  beri-beri.  Dilatation  of  the  right  side  of  the  heart 
is  reported  for  both  scurvy  and  beri-beri  in  terms  which  leave 
little  doubt  that  essentially  the  same  condition  is  being  described 
(35) .  Vedder  (36)  points  out  striking  similarity  in  the  nervous 
symptoms  observed  in  scurvy,  beri-beri  and  pellagra,  and  notes 
that  there  are  certain  resemblances  in  their  symptomatology  and 
pathology. 

240.  Two  or  More  Deficiency  Diseases  Doubtless  Fre- 
quently Occur  Together. — In  the  light  of  the  description  which 
has  been  given  of  the  dietary  properties  of  our  more  important 
natural  food-stuffs  and  the  products  manufactured  from  them, 
it  is  interesting  and  instructive  to  estimate  the  deficiencies  of 
typical  diets  which  have  been  described  as  having  occasioned 
numbers  of  cases  of  the  so-called  deficiency  diseases.  Thus,  in 
the  Burma  prison,  there  was  an  epidemic  of  scurvy  with  the  fol- 
lowing dietary  (37) : 

Oz.  Oz. 

Daily.  Daily. 

Rice  (husked)    24  Condiments    0.125 

Beans   4  Fish  paste    0.5 

Vegetables    (kinds    not    speci-  Salt  025 

fied)     10 

Oil    (vegetable)    0.5 

In  Southern  Rhodesia,  extensive  epidemics  of  scurvy  occurred 
in  mines  where  the  men  were  allowed  the  following  foods  (38) : 

Mealie  meal  (milled  maize) 2  Ib.  daily 

Meat 1  Ib.  weekly 

Beans 2  Ib.  weekly 

Monkey  nuts 1.5-2  Ib.  weekly 

Salt ad  lib. 

Chamberlain  (39)  in  1910  observed  that  among  5,000  Philip- 
pine Scouts  there  were  always  from  100  to  600  incapacitated  with 
beri-beri.  Their  diet  had  consisted  of  the  following  foods: 

Oz.  Daily. 

Beef    12 

White  flour   8 

Potatoes  or  onions  8 

Polished  rice    .  .  20 


214      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

On  changing  the  diet  by  substituting  16  ounces  of  unpol- 
ished rice  and  1.6  ounces  of  beans  for  the  twenty  ounces  of  pol- 
ished rice,  and  including  20  ounces  of  sweet  potatoes,  the 
number  of  cases  of  beri-beri  had  fallen  off  by  the  end  of  1910, 
to  fifty.  The  following  year  there  were  three  cases;  in  1912  but 
two,  and  no  cases  in  1913. 

241.  Comparison  Between  Diets  Which  Induce  Beri-Beri 
or  Scurvy,  with  Those  to  Which  Pellagra  Has  Been  Attri- 
buted.— Voegtlin  (40)  selected  the  following  diet  (Diet  A)  for 
one  hundred  patients  in  the  Pellagra  Hospital  at  Spartanburg, 
S.  C.,  who  were  suffering  from  mild  and  uncomplicated  pellagra. 
He  regards  this  as  typical  of  the  food  supply  of  numerous  homes 
where  cases  of  pellagra  are  observed. 

DIET  A  DIET  B 

Wheat  bread  300  grams.      Wheat  bread   300  grams. 

Butter  30  Butter  45 

Cabbage  100  Corn  meal   50 

Corn  meal   50  Eggs   100 

Ham   25  Meat   100 

Hominy  75  Orange  juice   100 

Corn  syrup  . : 30  Potatoes    150 

Pork    50  Prunes   30 

Potatoes    150  Sugar    40 

Prunes   30  Milk  1000 

Turnip  tops  100 

Sugar    40 

Milk  40 

Patients  restricted  to  Diet  A  failed  to  improve  or  grew  notice- 
ably worse.  They  were  later  changed  to  Diet  B,  which  differed 
essentially  in  containing  much  more  milk,  meat  and  eggs.  Most 
cases  showed  definite  improvement  within  two  weeks,  and  within 
two  months  or  more  they  were  pronounced  cured,  except  in  a  few 
more  severe  and  advanced  cases.  The  therapeutic  value  of  the 
dietetic  treatment  was  very  spectacular. 

Goldberger  and  Wheeler  (41)  undertook  to  determine  whether 
adherence  to  a  diet  composed  in  great  measure  of  milled  cereal 
products,  sugar,  syrup,  potatoes  and  fat  meat  would  cause  pel- 
lagra to  develop  in  man.  This  was  tested  out  on  eleven  healthy 
adult  men  in  the  Mississippi  state  prison  in  1915.  The  men 
volunteered  to  submit  to  the  test  for  the  reward  of  pardon  after 
six  months'  adherence  to  the  experimental  diet. 

The  following  list  of  foods  with  their  amounts,  representing 
the  diet  per  man  per  day  for  the  week  ending  September  13, 1915, 


THE  DIETARY  DEFICIENCY  DISEASES          215 

is  typical  of  the  diets  employed  with  a  view  to  the  experimental 
production  of  pellagra  in  man: 

Corn  meal   253.0  grams.     Sweet  potatoes    100.0  grams. 

Grits    38.7  Turnip  greens    7.3 

Corn  starch   34.0  Cabbage    10.7 

Wheat  flour  150.3  Collards    24.6 

Rice,  polished 19.8  Pork  fat  1122 

Cane  syrup  27.3 

Cane  sugar  57.8 

This  was  regarded  as  comparable  in  its  constitution  and  quan- 
titative relations  with  diets  taken  by  pellagrins.  With  this  diet 
Goldberger  secured  results  which  leave  little  room  for  doubt 
that  men  confined  to  it  for  a  period  of  six  months  developed 
incipient  signs  of  pellagra  (41). 

It  is  impossible  to  say,  from  a  study  of  these  diets  why  the 
two  first  mentioned  should  produce  scurvy  rather  than  pellagra. 
This  is  especially  true  of  the  diet  of  the  miners  of  Rhodesia.  It 
seems  equally  remarkable  that  the  diet  reported  by  Chamberlain 
caused  beri-beri  rather  than  pellagra,  for  so  far  as  one  can  judge 
from  the  results  of  feeding  experiments  with  animals,  there  are 
no  special  qualities  in  beef  which  could  differentiate  it  from  other 
foods  in  respect  to  any  dietary  essential  which  we  should  have 
reason  to  believe  would  induce  a  specific  syndrome.  The  pos- 
sibility is  not  excluded,  of  course,  that  pellagra  is  a  disease  which 
cannot  be  produced  in  those  species  of  experimental  animals 
which  have  been  employed,  because  of  the  presence  of  synthetic 
powers  of  a  specific  type  not  possessed  by  man.  The  proof  that 
the  rat  and  prairie  dog  on  certain  diets  can  synthesize  the  anti- 
scorbutic substance,  affords  an  illustration  of  a  case  where  this 
is  true. 

242.  Appleton's  Observations  on  the  Diet  of  Newfoundland 
and  Labrador. — Appleton  (42)  has  contributed  valuable  data 
relating  to  the  character  of  the  diet  of  the  people  of  Labrador 
along  the  Straits  of  Belle  Isle,  and  also  observations  on  the  rela- 
tion of  the  faulty  food  supply  to  the  incidence  of  deficiency  dis- 
eases. Under  their  dietary  practises  beri-beri,  scurvy,  edema 
and  ophthalmia  of  dietary  origin  are  of  fairly  common  occur- 
rence, and  Dr.  Appleton  reports  a  single  case  of  pellagra.  This 
last  observation  is  of  extraordinary  importance,  for  it  is  very 
unlikely  that  the  patient  should  have  been  exposed  to  the  disease, 
and  its  occurrence  in  this  isolated  region  in  sporadic  cases,  would 
seem  to  support  the  view  that  it  is  a  deficiency  of  some  kind  in 
the  diet  which  produces  it. 


216     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

The  striking  thing  about  Appleton's  report,  is  that  sometimes 
one  and  sometimes  another  of  the  deficiency  diseases  develops 
among  people  whose  diet  is  so  similar  in  different  households. 
The  entire  population  is  evidently  in  a  state  of  extreme  nutri- 
tional instability,  and  small  deviations  of  the  constitution  of  the 
diet  determine  which  disease  will  appear.  The  following  table 
gives  the  approximate  consumption  of  their  principal  articles 
of  diet. 

Bolted  wheat  flour  1*4  to  1%  barrels  per  person  per  year. 

Salt  meats,  pork  or  beef 1  or  2  barrels      for  a  family  of  eight. 

Salt  codfish    , 2   to  4   quintals 

Salt   herring    1  to  3  barrels 

Molasses    160  gallons 

Potatoes    1  to  2  barrels 

Rutabagas   1  to  2  barrels 

Dried  peas    20  to  40  gallons 

Raisins    10  to  20  pounds 

Butter  substitute   160   pounds 

Condensed  or  evaporated  milk.  From  a  few  tins  to  two  cases. 

Tea    20  to  40  pounds  per  year  for  family  of 

eight. 

Meat,  salt  fish,  potatoes  and  dried  peas  are  eaten  only  once 
or  twice  a  week  and  the  supply  may  become  exhausted  in  April. 
Game  is  scarce  and  is  little  eaten.  Fresh  trout,  cod  and  salmon 
are  caught  only  during  the  summer.  Small  quantities  of  rice, 
onions  or  dried  beans  are  occasionally  secured,  but  only  rarely. 
Gardening  is  little  practised,  but  in  favorable  seasons  enough 
cabbage  may  be  grown  to  last  until  November.  Poultry  are  not 
kept  as  a  rule  and  egg  powder  is  imported  only  in  sufficient 
amounts  for  making  cakes  for  fetes.  The  only  fresh  fruit  ever 
eaten  are  partridge  berries  and  another  little  yellow  berry  called 
locally  "baked  apple."  Tea  is  consumed  in  enormous  amounts, 
ten  to  eighteen  cups  a  day  being  not  unusual. 

243.  The  Dietary  Deficiency  Diseases  Must  Occur  Rarely 
in  Man  in  the  Uncomplicated  Forms. — The  specimen  diets 
which  are  given  above  have  another  meaning  aside  from  that  just 
discussed.  They  show  that  on  any  of  these  diets  a  man  would 
not  suffer  from  a  single  deficiency,  but  from  several,  and  that 
where  scurvy  was  observed  it  seems  evident  that  there  must  have 
been  likewise  a  serious  shortage  of  the  anti-neuritic  substance, 
and  consequently  a  tendency  for  symptoms  of  neuritis  to  develop. 
Furthermore  the  diets  listed  are  all  decidedly  deficient  in  one 
or  more  inorganic  elements,  notably  calcium.  In  these  diets 


THE  DIETARY  DEFICIENCY  DISEASES          217 

poor  in  meat  there  was  likewise  a  serious  shortage  of  phosphorus 
as  measured  by  the  requirements  of  the  rat. 

It  seems  extremely  probable,  therefore,  that  in  many  instances 
where  one  of  the  diseases,  beri-beri  or  scurvy,  is  diagnosed,  the 
other  exists  as  a  complicating  condition.  This  would  account 
for  the  points  of  similarity  in  the  manifestations  of  the  two  dis- 
eases as  they  have  been  described  by  several  observers.  It  also 
raises  the  question  as  to  whether  the  specific  effects  of  lack  of 
the  anti-scorbutic  substance  or  of  the  anti-neuritic  substance,  the 
remaining  components  of  the  diet  being  of  optimal  quality,  can 
be  said  to  be  fully  known,  at  least  in  the  human  subject. 

244.  The  Prevention  of  Deficiency  Diseases  Does  Not  Nec- 
essarily   Insure   Good   Nutrition. — It    should    be   emphasized, 
finally,  that  the  addition  to  such  a  diet  as  is  ordinarily  observed 
in  the  Orient  to  produce  beri-beri,  of  some  article  of  food  which 
will  prevent  the  development  of  beri-beri,  will  in  many  instances 
not  go  far  toward  correcting  inorganic  faults.     From  the  stand- 
point of  public  health,  therefore,  it  is  by  no  means  sufficient  to 
prevent  beri-beri  in  those  countries  where  it  occurs.     This  may 
be  effectually  accomplished,  and  yet  the  population  may  still  be 
inefficient  physically,  and  suffer  from  high  infant  mortality  be- 
cause of  the  poor  quality  of  the  mother's  milk,  and  the  adult 
members  of  the  population  may  still  early  develop  signs  of  sen- 
ility.   These  statements  are  made  on  the  basis  of  the  assump- 
tion that  the  same  physiological  limitations  with  respect  to  nutri- 
tion, which  apply  to  animals  apply  with  equal  force  to  man,  and 
that  these  run  parallel  when  the  comparison  of  an  animal  with  a 
man  on  the  same  diet  is  made  on  experiments  covering  equivalent 
fractions  of  the  average  span  of  life  of  which  each  is  capable. 

245.  Borderline    Malnutrition,    Not    Causing    Alarm,    of 
Greater  Aggregate  Importance  Than  Deficiency  Diseases. — 
The  data  presented  in  this  chapter,  relative  to  the  character  of 
the  diets  of  several  groups  of  people  in  relation  to  the  types  of 
nutritive  disaster  which  overtook  them,  serve  well  the  purpose 
of  illustrating  the  soundness  of  the  proposition  which  is  empha- 
sized throughout  this  study  of  the  relation  of  man's  diet  to  physi- 
cal well-being,  viz.:  the  danger  to  health  in  the  adherence  to  a 
diet  in  which  milled  cereal  products,  sugar,  syrup,  tubers  and 
meats  of  the  muscle  type  predominate.     Such  a  diet  is  unsafe  to 
a  degree  which  makes  it  a  matter  of  national  importance. 

It  is  especially  important  that  the  public  be  educated  to  a 
realization  of  the  danger  of  poor  physical  development,  poor 


218      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

teeth,  low  health  standards,  physical  inefficiency  and  early  aging, 
which  such  a  type  of  diet  is  sure  to  bring  about.  The  alarming 
increase  in  the  incidence  of  malnutrition  among  children,  and 
the  need  for  dental  repair,  together  with  the  train  of  ills  from 
which  the  present  generation  of  adults  is  suffering,  and  which 
may  safely  be  traced  to  faulty  development  and  bad  teeth,  are 
in  great  measure  the  result  of  the  poor  quality  of  the  diet  of 
expectant  and  nursing  mothers  and  of  children.  It  will  be  ap- 
parent from  what  has  been  said,  that  it  has  become  the  general 
custom  in  many  parts  of  Europe  and  America,  to  adhere  to  a 
diet  which  is  but  little  better  than  those  which  in  restricted  areas 
are  actually  producing  clinically  recognizable  diseased  conditions. 
General  observations  should  convince  anyone  that  we  are  now, 
as  a  nation,  falling  far  short  of  the  physical  perfection  which 
would  result  from  an  improved  dietary. 

The  observations  of  McCarrison  afford  very  suggestive  evi- 
dence that  nutritive  disturbances  referable  to  faulty  digestion 
with  their  far-reaching  consequences  for  the  health  of  the  indi- 
vidual, are  to  be  referred  to  borderline  malnutrition  brought 
about  by  food  which  does  not  meet  the  nutritive  needs  of  the 
body.  Our  present  living  habits  are  characterized  by  too  great 
consumption  of  bolted  flour,  degerminated  cornmeal,  breakfast 
cereals,  and  other  seed  products,  tubers  and  muscle  meats.  We 
are  taking  too  little  of  the  protective  foods,  milk  and  the  leafy 
vegetables,  and  a  movement  toward  stimulating  the  consumption 
of  these  classes  of  foods,  would  go  far  toward  effecting  that  im- 
provement in  our  national  health  standards,  for  which  the  many 
agencies  concerned  with  the  public  health  are  seeking. 

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July  9,  86. 

3.  Hoist,  A.:    The  etiology  of  beri-beri,  Soc.  Trop.  Med.  and  Hyg.,  1911, 

v,  76. 

4.  Eijkman,    C.:     Ein    Versuch    zur    Bekampfung    Beri-beri,    Virchow's 

Archiv,  1897,  cxlix,  187. 

Ein  Beri-beri  anliche  Erjtrankung  der  Hiihner,  Ibid.,  1897,  cxlviii,  523. 

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Thier-chemie,  1897,  xxvii,  729. 

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THE  DIETARY  DEFICIENCY  DISEASES          219 

8.  Schaumann,    H.:     Die    Etiologie    der    Beri-beri,    Arch.    f.   Schiffs-    u. 

Tropen-Hyg.,  1914,  xviii,  Beihefte  6. 

Neuere  Ergebnisse  der  Beri-beri  Forschung,  Ibid.,  1915,  xix,  393. 
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Gerrard,  P.  N.:     The  influence  of  rainfall  on  beri-beri,  Lancet,  1899, 

I,  367,  Feb.  11. 

13.  Manson,  P.:     The  etiology  of  beri-beri,  Lancet,  1901,  1391,  Nov.  23. 

14.  Ross,  R.:    Beri-beri  and  arsenical  poisoning,  Lancet,  1901,  1058,  Oct.  19. 

15.  Edie,  E.  S.,  and  Simpson,  G.  C.  E.:     The  preparation  of  various  food- 

stuffs (especially  wheat  and  rice).  Its  effect  on  their  content  of 
organic  phosphorus  compounds  and  its  relations  to  a  disease,  Brit. 
Med.  Jour.,  1911,  June  17. 

16.  Fletcher,  W.:    Rice  and  beri-beri,  Lancet,  1907,  i,  1776. 

Rice  and  beri-beri,  Jour.  Trop.  Med.  Hyg.,  1908,  xii,  127. 

17.  Funk,  C.:     Further  studies  on  experimental  beri-beri:   the  action  of 

certain  purines  and  pryimidine  derivatives,  Jour.  Physiol.,  1912-13, 
xlv,  489. 

Chemistry  of  the  vitamine  fraction  from  yeast  and  rice  polishings, 
Ibid.,  1913,  xlvi,  173. 

18.  Funk:     Studies  on  beri-beri.     The  probable  role  of  vitamins  in  the 

process   of  digestion  and  utilization   of   food,  Proc.   Physiol,   Soc., 

Dec.  13,  1913. 

Experimentelle  Beweise   gegen  die  toxische  Theorie   der  Beri-beri, 

Zeit.  f.  physiol.  Chem.,  1914,  Ixxxix,  373. 

Die  Rolle  der  Vitamine  beim  Kohlenhydrat-Stoffwechsel,  Ibid.,  1914, 

Ixxxix,  378. 

19.  Suzuki,   U.,   Shimamura,   T.,    and    Odake,   S.:      Ueber    Oryzam'n,    ein 

Bestandteil  der  Reiskleie  und  seine  physiologische  Bedeutung, 
Biochem.  Zeit.,  1912,  xliii,  89. 

20.  Chamberlain,  W.  P.,  and  Vedder,  E.  B.:     Contributions  to  the  etiology 

of  beri-beri,  Philippine  Jour,  of  Sci.,  B.,  1911,  vi,  251,  395. 

21.  Edie,  E.  S.,  Evans,  E.  H.,  Moore,  B.,  Simpson,  G.  C.  E.,  and  Webster, 

A.:  The  anti-neuritic  bases  of  vegetable  origin  in  relationship  to 
beri-beri,  with  a  method  of  isolation  of  torulin,  the  anti-neuritic 
base  of  yeast,  Biochem.  Jour.,  1912,  vi,  234. 

22.  Kohlbriigge,  J.  H.  T.:     Die  Gahrungskrankheiten  (Beri-beri,  Skorbut, 

Barlowsche  Krankheit,  Cholera  nostras,  u.  a.,  Zeit.  f.  Bakt.  Orig., 
1911,  Ix,  223. 

23.  Wright,  A.  E.:     The  causation  and  treatment  of  scurvy,  Lancet,  1908, 

II,  725. 

The  pathology  and  therapy  of  scurvy,  Army  Med.  Rept.  1895, 
Maly's  Jahres-Bericht  d.  Thier-Chemie,  1897,  xxvii,  754. 


220      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

24.  Hoist,   A.,   and   Frolich,  T.:      Experimental   studies  relating  to   ship 

beri-beri  and  scurvy,  Jour.  Hyg.,  1907,  vii,  634. 

25.  Digby,  W.:     The  famine  campaign  in  Southern  India,  1876-1877. 

26.  Patterson,  A.  H.:     Starvation  edema,  Med.  Rec.,  1899,  715. 

Mann,  W.  L.,  Helm,  J.  B.,  and  Brown,  C.  J.:     An  edema  disease  in 
Haiti,  Jour.  Amer.  Med.  Assoc.,  1920,  Ixxv,  1416. 

27.  Wagner,  E.:     Die  sogenannte  essentielle  Wassersucht,  Deutsche  Arch. 

f.  klin.  Med.,  1887,  xli,  509. 

28.  Potter,  P.  A.:     The  relation  of  protein  to  edema  in  marantic  children, 

Med.  News,  New  York,  Jan.  9,  1904. 
Edema  in  infants,  Archiv.  Pediat.,  1912,  xxix,  206. 

29.  Czerny,  A.,  and   Keller,  A.:     Des  Kindes   Ernahrung,  Leipsic,  1906, 

part  2,  67. 

30.  Hoist,  A.:    The  etiology  of  beri-beri,  Trans.  Soc.  Trop.  Med.  and  Hyg., 

1911,  v,  76. 

31.  Budzynzki,    B.,    and    Chelshowski,    J.    M.    H.:      Hunger   swelling    in 

Poland,  Jour.  Trop.  Med.,  1916,  xix,  141. 

32.  Maver,  M.  B.:    War  edema,  Jour.  Amer.  Med.  Assoc.,  1920,  Ixxiv,  934, 

April  3. 

33.  Denton,  M.,  and  Kohman,  E.  A.:     Feeding  experiments  with  raw  and 

boiled  carrots,  Jour.  Biol.  Chem.,  1918,  xxxvi,  249. 

34.  Kohman,  E.  A.:     The  experimental  production  of  edema  as  related 

to  protein  deficiency,  Amer.  Jour.  Physiol.,  1920,  li,  378. 

35.  Hess,  A.  F.,  and  Fish,  M.:     Infantile  scurvy:     The  blood,  the  blood 

vessels,  and  the  diet,  Amer.  Jour,  of  Dis.  of  Child.,  1914,  viii,  386. 
McCarrison,    R.:      The    influence    of   dietaries    deficient    in    accessory 

food  factors  on  the  intestine,  Indian  Jour,  of  Med.  Research,  1919, 

vii,  167. 
Hess:    Subacute   and  latent   infantile   scurvy.     The    cardiorespiratory 

syndrome,  Jour.  Amer.  Med.  Assoc.,  1917,  Ixviii,  235. 

36.  Vedder,  E.  B.:    Dietary  deficiency  as  the  etiological  factor  in  pellagra, 

Arch.  Int.  Med.,  1916,  xviii,  137. 

37.  Burma  prison  diet.     Editorial  in  Bulletin  of  Tropical  Diseases,  1914, 

iv,  446. 

38.  Fleming,   Macaulay,   and   Clark,   Southern   Rhodesia   Mines.     Report 

on   the   prevalence   and   prevention   of   scurvy   and   pneumonia  in 
Southern  Rhodesia  amongst  native  laborers,   1910. 

39.  Chamberlain,  W.  P.:    Prevention  of  beri-beri  among  Philippine  Scouts 

by  means  of  modifications  in  the  diet,  Jour.  Amer.  Med.  Assoc., 
1915,  Ixiv,  1215. 

40.  Voegtlin,  C.:     Recent  work  on  pellagra,  Harvey  Lectures,  1920.    Pub. 

Health  Rep.,  1920,  xxxv,  1435,  June  18. 

41.  Goldberger,  J.,  and  Wheeler,  G.   A.:     Experimental   pellagra  in  the 

human  subject,  Jour.  Amer.  Med.  Assn.,  1916,  Ixvi,  471;   Hygienic 
Lab.  Bull.  No.  120. 

42.  Appleton,  V.   B.:      Observations   on   diet   in   Labrador,   Jour.   Home 

Econ.,  1921,  xiii,  199. 

Appleton:      Observations    on    the    deficiency    diseases    of    Labrador, 
American  Journal  of  Public  Health,  1921,  xi,  617. 


CHAPTER  X 

THE  CHEMICAL  NATURE  OF  THE  ANTI-NEURITIC 
SUBSTANCE,  WATER-SOLUBLE  B 

246.  Schaumann's  Views  on  the  Nature  of  the  Anti-Beri- 
Beri  Substance. — In  the  preceding  chapter  it  was  described  how 
Schaumann,  who  was  the  first  to  extend  the  suggestive  studies 
of  Eijkman,  attempted  to  identify  the  substance  in  rice  polish- 
ings,  which  effects  a  cure  of  polyneuritis  or  experimental  beri- 
beri in  pigeons.     He  observed  that  polished  rice  has  a  much 
lower  phosphorus  content  than  unpolished,  and  that  the  polish- 
ings  which  are  extremely  rich  in  this  element  are  highly  effective 
in  preventing  or  curing  the  disease.    These  facts  led  him  to  sug- 
gest that  the  substance  under  investigation  was  of  the  nature 
of  a  nucleic  acid.    Nucleic  acid  is  a  substance  occurring  in  the 
nuclei  of  all  cells  of  animal  and  vegetable  origin.     It  is  an  organic 
complex  composed  of  four  organic  bases,  four  molecules  of  sugar 
and  four  molecules  of  phosphoric  acid.    This  view  he  later  aban- 
doned when  he  was  able,  in  1912,  to  isolate  from  rice  bran  a 
phosphorus-free  substance  which  would  save  from  death,  pigeons 
suffering  from  polyneuritis.    He  suggested  that  it  functioned  in 
a  manner  analogous  to  an  enzyme,  and  since  it  was  closely  asso- 
ciated with  the  areas  in  the  rice  kernel  in  which  phosphorus  is 
abundant,  he  believed  that  it  had  some  relation  to  the  deposition 
of  phosphorus. 

247.  Funk's   Studies    on    the    Isolation    of   "Vitamine." — 
Funk  (1)  made  the  first  elaborate  effort  to  isolate  and  identify 
the  anti-beri-beri  vitamin.     He  found  that  alcohol  would  ex- 
tract a  part  of  the  physiologically  active  substance  from  rice 
polishings  but  that  water  was  a  far  more  effective  solvent.    From 
such  solutions  it  can  be  precipitated  by  phosphotungstic  acid  or 
by  silver  nitrate  and  barium  hydroxid,  and  also  partially  by 
mercuric  chlorid.    By  means  of  the  systematic  procedure  ordi- 
narily employed  for  the  separation  of  mixtures  of  organic  bases, 
Funk  established  the  fact  that  the  curative  substance  contains 
nitrogen  and  is  free  from  phosphorus.     He  believed  at  one  time 

221 


222      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

that  he  had  definite  evidence  that  it  belonged  to  the  class  of 
organic  compounds  known  as  pyrimidins. 

It  has  been  the  experience  of  all  investigators  that  the  farther 
the  substances  possessing  curative  properties  are  purified,  the  less 
effective  they  become.  This  suggests  that  the  important  sub- 
stance sought  is  not  a  crystallizable  body,  and  that  the  crystals 
of  definite  and  identifiable  compounds  thus  far  obtained  are 
merely  contaminated  with  the  nutritive  principle. 

248.  Other  Suggestions  as  to  the  Nature  of  the  Anti-Beri- 
Beri  Substance. — The  preparation  described  by  Suzuki,  Shima- 
mura  and  Odake,  and  called  by  them  oryzanin  was  certainly  not 
a  distinct  compound,  but  a  relatively  complex  mixture  of  sub- 
stances extracted  from  rice  polishings  (2) . 

Edie,  Evans,  Moore,  Simpson  and  Webster  (3)  obtained  an 
active  fraction  from  yeast,  which  they  regarded  as  belonging  to 
the  pyrimidin  group.  This  preparation  they  termed  torulin. 

Williams  and  Seidell  (4)  prepared  a  sample  of  adenin  from 
yeast,  and  found  that  it  had  curative  properties  for  polyneuritis 
in  pigeons,  but  these  were  lost  on  keeping.  They  attributed  the 
change  in  the  physiological  effect  of  the  adenin  relative  to  its 
anti-neuritic  properties  to  molecular  arrangement.  The  loss  of 
anti-neuritic  power  they  attributed  to  the  gradual  passing  over 
of  an  unstable  compound  into  a  stable  form.  Voegtlin  and 
White  (5)  and  Harden  and  Zilva  (6)  have  been  unable  to  con- 
firm these  observations. 

Abderhalden  and  Schaumann  (7)  have  published  a  paper  in 
which  they  describe  attempts  to  isolate  the  anti-neuritic  sub- 
stance from  yeast.  They  introduced  two  new  terms  (eutonin 
and  nutramin) ,  but  otherwise  made  no  advance  toward  the  solu- 
tion of  the  problem  of  isolating  the  anti-neuritic  complex. 

Hofmeister  (8)  reported  that  he  had  isolated  a  substance  which 
he  identified  as  a  pyrimidin,  and  which  possessed  anti-neuritic 
properties. 

Funk  and  others  isolated  nicotinic  acid  from  rice  polishings. 
The  idea  has  been  expressed  that  this  or  some  unstable  modifica- 
tion thereof,  is  the  anti-neuritic  substance.  Extracts  of  rice 
polishings  prepared  according  to  the  usual  procedure  for  securing 
the  "vitamin  fraction,"  have  been  observed  to  develop  a  pyridin- 
like  odor.  Furthermore,  Drummond  and  Funk  (9)  noted  that 
preparations  which  were  capable  of  curing  pigeons  of  poly- 
neuritis  always  gave  the  characteristic  blue  color  with  the  Folin- 
Macallum  phenol  reagent,  indicating  the  presence  of  a  substance 
or  substances  containing  hydroxyl  groups  (10). 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B    223 

249.  Williams'    Investigations    on    Hydroxy    Pyridins.— 
Acting  on  this  clue,  Williams  (11)  prepared  certain  a-hydroxy 
pyridins  and  tested  them  for  anti-neuritic  properties  by  injecting 
them  into  polyneuritic  pigeons.    A  number  of  cures  were  effected. 
On  keeping,  these  preparations  lost  within  a  few  days  all  cura- 
tive power.    From  these  findings  Williams  drew  the  deduction 
that  the  substances  underwent  a  spontaneous  change  from  an 
unstable  to  a  stable  form  and  that  the  latter  was  inactive.    By 
treatment  of  inactive  preparations  with  alcoholic  sodium  hy- 
droxid  he  found  it  possible  to  transform  them  into  the  physio- 
logically active  condition.    From  the  method  of  manipulation 
and  treatment,  he  was  justified  in  assuming  that  he  had  in  the 
active  preparation  the  enol  form  of  the  substance.    None  of 
Williams'  synthetic  preparations  had  anything  like  the  activity 
or  certainty  of  action  that  is  seen  in  extracts  of  certain  natural 
foods.     He  was  led  to  surmise  that  the  pathological  condition 
of  polyneuritis  is  not  due  to  a  deficiency  of  a  substance  per  se, 
but  to  a  lack  of  a  certain  type  of  potential  energy  which  only 
certain  substances  can  supply.    In  other  words,  he  suggested 
that  it  was  the  potentiality  of  isomeric  change,  in  the  substance 
administered,  which  produced  the  physiological  effect  of  restor- 
ing function  to  a  paralyzed  bird.    To  this  isomeric  change,  Wil- 
liams attributed  the  instability  of  the  vitamins  of  natural  foods. 
He  did  not  draw  the  conclusion  that  the  anti-neuritic  vitamin 
is  a  hydroxy-pyridin,  but  pointed  out  that  the  same  type  of 
isomerism  is  possible  in  bodies  of  entirely  unrelated  natures  such 
as  pyrimidins,  purins  and  other  heterocyclic  compounds. 

250.  Williams  and  Seidell's  Activation  of  Adenin. — In  a 
later  publication  Williams  and  Seidell  (4)   adsorbed  by  means 
of   fuller's   earth   the   anti-neuritic    substance   from   autolyzed 
yeast.    They  then  extracted  the  active  material  from  the  inor- 
ganic earth  by  means  of  5  per  cent  sodium  hydroxid.    This 
procedure  was  said  not  to  cause  in  the  substance  a  loss  of  anti- 
neuritic   property.    The   extracted   material   was   subjected   to 
crystallization,  but  the  crystals  were  found  to  be  inactive  and 
were  identified  as  adenin,  one  of  the  purins.    When  adenin  was 
treated  with  boiling  glacial  acetic  acid,  acetic  anhydrid,  dilute 
hydrochloric  acid  or  sulphuric  acid,  or  allowed  to  stand  for  some 
time  in  the  presence  of  dilute  mineral  acids  or  heated  to  boiling 
with  concentrated  sulphuric  acid  it  was  reported  to  have  ac- 
quired anti-neuritic  properties. 

The  deduction  drawn  by  the  authors  from  their  data  was  that 
"an  isomer  of  adenin  is  the  chemical  entity  responsible  for  the 


224      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

characteristic  physiological  properties  of  the  vitamin  under  in- 
vestigation." It  is  difficult  to  understand  why,  after  obtaining 
their  adenin  from  yeast,  in  a  manner  well  known  to  lead  to  a 
partial  isolation  of  the  anti-neuritic  substance,  and  after  identi- 
fying adenin  as  a  component  of  the  mixture  prepared  by  their 
procedure,  and  after  having  denaturized  the  substance  so  to 
speak,  and  finally  having  treated  it  so  as  to  confer  upon  it  once 
more  pronounced  anti-neuritic  properties,  these  investigators 
should  have  placed  such  a  modest  estimate  upon  the  significance 
of  their  results.  They  stated  that  they  regarded  their  work  as 
"of  chief  interest  not  in  its  contribution  toward  establishing  the 
composition  or  identity  of  this  "vitamin,"  which  may  or  may  not 
be  a  unique  compound,  but  in  affording  corroboration  of  the 
theory  advanced  that  isomerism  plays  a  determinative  role  in 
the  physiological  potency  of  vitamins."  It  would  seem  justi- 
fiable under  such  conditions  to  assume  that  adenin,  existing  in  a 
peculiar  modification  in  yeast,  is  probably  either  the  sole,  or  at 
least  one  of  the  actual  entities  which  exert  the  anti-neuritic 
effect. 

In  a  later  paper  Williams  (12)  again  has  expressed  the  view 
that  under  certain  conditions  a-hydroxy  pyridin  may  possess 
anti-neuritic  properties.  He  attributed  these  properties  to  the 
existence  of  this  compound  in  the  form  of  a  pseudo-betain,  and 
suggested  that  a  configuration  conforming  more  or  less  closely 
to  that  of  the  betain  ring  was  probably  an  essential  charac- 
teristic of  the  anti-neuritic  vitamin.  It  was  pointed  out  that 
such  a  structure  was  possible  in  most  of  the  simpler  nitrogenous 
components  of  animal  tissues,  especially  in  the  purin  bases. 

The  anti-neuritic  substance  is  relatively  stable  toward  acids, 
but  undergoes  a  change  of  some  sort  when  treated  with  alkalies 
so  as  to  lose  its  physiological  value.  Sullivan  and  Voegtlin  ob- 
served this  destructive  effect  of  alkalies,  and  their  observations 
have  been  confirmed  by  McCollum  and  Simmonds  and 
others  (12). 

251.  SeidelTs  Silver  Compound. — Recently  Seidell  (13)  has 
described  a  method  for  the  preparation  of  a  relatively  stable 
silver  compound  of  the  anti-neuritic  substance.  He  discovered 
that  fuller's  earth  has  the  property  of  absorbing  from  its  solu- 
tions the  physiologically  active  substance  which  exerts  an  anti- 
neuritic  effect.  In  this  way  it  can  be  separated  from  certain 
other  substances  with  which  it  is  associated.  From  the  fuller's 
earth  the  vitamin  is  extracted  by  barium  hydroxid.  The  barium 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B    225 

is  quickly  removed  from  the  resulting  extract  as  sulphate  and 
lead  acetate  is  subsequently  added  as  a  precipitant.  The  excess 
of  lead  is  removed  as  sulphid,  and  the  filtrate  from  this  precipi- 
tate is  evaporated  rapidly  under  diminished  pressure  to  a  small 
volume,  when  a  white  amorphous  substance  separates.  This 
is  found  to  be  inactive  and  is,  therefore,  discarded.  Evaporation 
is  continued  in  a  vacuum  desiccator  and  several  crops  of  the 
white  substance  are  secured  and  removed.  The  solution,  which 
possesses  great  anti-neuritic  activity,  is  finally  evaporated  to  a 
thick  viscous  mass  which  can  be  finally  brought  to  dryness. 
The  physiological  activity  of  the  dried  residue  is  retained  for 
many  months. 

When  this  material  is  dissolved  in  a  small  volume  of  water 
and  treated  with  silver  nitrate,  there  is  formed  a  voluminous 
precipitate,  which  does  not  contain  the  anti-neuritic  substance. 
This  precipitate  is  removed.  To  the  filtrate  silver  nitrate  and 
ammonium  hydroxid  are  added.  These  reagents  form  a  second 
silver  precipitate  which  contains  the  desired  vitamin.  The  filtrate 
is  practically  free  from  it.  This  procedure  appears  to  be  a  dis- 
tinct step  in  advance  in  the  purification  of  this  most  interesting 
principle. 

McCollum  and  Kennedy  (13)  conducted  experiments  with 
pigeons  designed  to  show  the  importance  of  fat-soluble  A  as  a 
factor  in  the  etiology  of  experimental  beri-beri,  and  to  determine 
whether  definite  evidence  could  be  secured  as  to  whether  the 
growth  essential  water-soluble  B,  which  had  been  demonstrated 
on  rats,  was  identical  with  the  substance,  specific  starvation  for 
which  leads  to  beri-beri  in  birds.  Their  data  indicated  that  any 
extracts  of  natural  foods  which  furnish  water-soluble  B  in  growth 
tests  with  rats  likewise  effected  "cures"  of  beri-beri  pigeons. 
They  were  able  to  demonstrate  that  fat-soluble  A  plays  no  role 
in  the  production  of  experimental  beri-beri  in  pigeons.  These 
authors  also  found  that  acetone,  ethyl  acetate  and  benzene  can 
extract  from  wheat  germ,  rendered  fat  free  by  extraction  with 
ether,  the  anti-neuritic  substance.  It  is  now  known,  however, 
that  these  solvents  are  extremely  inefficient  for  this  purpose,  and 
that  not  more  than  traces  of  the  active  substance  can  be  isolated 
by  their  use  as  solvents. 

252.  Robertson's  Observations  on  Tethelin. — In  this  con- 
nection the  work  of  Robertson  (13)  should  be  mentioned.  He 
separated  a  crude  lipoid  fraction  from  the  anterior  lobe  of  the 
pituitary  of  the  ox  to  which  he  gave  the  name  tethelin.  He  car- 


226     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

ried  out  extensive  experiments  on  the  growth  of  mice  designed 
to  show  the  effect  of  tethelin.  There  was  offered  no  evidence 
that  a  definite  substance  was  isolated,  for  no  adequate  attempt 
was  made  to  purify  the  active  principle  which  it  was  believed 
to  contain.  Furthermore,  the  substance  was,  in  his  experiments, 
superimposed  upon  a  mixed  diet  of  considerable  complexity, 
which  was  adequate  for  the  nearly  normal  nutrition  of  the  mouse. 
It  is  not  possible  to  intelligently  discuss  Robertson's  results, 
therefore,  in  connection  with  the  dietary  problems  which  form 
the  theme  of  this  book. 

253.  Myers  and  Voegtlin's  Procedure  for  Isolating  the  Anti- 
Beri-Beri  Substance. — Myers  and  Voegtlin  (14)  report  that  they 
have  been   able    to   remove   the   anti-neuritic   substance   from 
autolyzed  yeast  by  means  of  its  solubility  in  olive  oil  or  in  oleic 
acid.    They  state  that  it  is  also  soluble  in  acidified  methyl  alco- 
hol, and  can  be  extracted  from  unautolyzed  (dry)  yeast  by  this 
solvent. 

It  will  be  seen  from  the  foregoing,  that  but  little  progress 
has  been  made  in  devising  methods  for  accumulating  consider- 
able amounts  of  the  anti-neuritic  substance  or  for  determining 
its  identity.  There  are  other  confusing  factors  which  enter  into 
studies  of  this  character  and  which  are  not  generally  appre- 
ciated. One  of  these  is  that  the  results  of  several  investigators 
have  indicated  that  compounds  of  several  kinds,  including 
purins,  pyrimidins  and  pyridins,  have  induced  at  least  tempo- 
rary "cures"  in  pigeons  suffering  from  polyneuritis.  Still  more 
recently  Butcher  (15)  has  reported  "cures"  of  pigeons  as  the 
result  of  administering  such  physiological  stimulants  as  adren- 
alin and  pilocarpin,  both  of  which  are  absent  from  all  ordinary 
foods. 

254.  Harden  and  Zilva  Fail  to  Confirm  the  Experiments  of 
Williams  and  Seidell. — Harden  and  Zilva    (16)    and  Voegtlin 
and  White  (17)  have  attempted  to  repeat  the  studies  of  Williams 
and  Seidell  purporting  to  show  that  adenin  and  a-hydroxy  py- 
ridin  can   acquire   anti-neuritic   properties.     In   all   their   tests 
they  found  no  evidence  that  these  compounds  exert  any  curative 
action  on  pigeons  suffering  from  polyneuritis.     McCollum  and 
Koch  (18)  have  attempted  to  induce  growth  in  young  rats  on 
diets  lacking  only  the  anti-neuritic  substance^  but  containing 
instead  adenin,  pilocarpin  hydrochlorid  or  adrenalin.     In  no  in- 
stance  was  there  the  slightest  indication  that  the  physiologically 
indispensable  complex  was  supplied  by  any  of  these  compounds. 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B    227 

McCollum  and  Simmonds  (19)  also  tested  thymus  nucleic  acid 
as  a  source  of  the  anti-neuritic  principle,  but  with  negative  re- 
sults. 

255.  Me  Garrison's  Investigations  on  Beri-Beri  in  Birds  and 
Mammals. — A  new  conception  of  the  pathology  of  polyneuritis 
and  other  "deficiency"  diseases  was  introduced  by  McCarrison 
(20) .  The  most  striking  manifestations  of  beri-beri  are  the  loss 
of  the  coordinating  powers  of  the  muscles.  The  onset  of  the 
disease  is  generally  preceded  by  the  bird  sitting  with  ruffled 
feathers,  and  with  the  appearance  of  illness.  There  is  progres- 
sive weakness,  and  when  disturbed  there  is  a  tendency  for  many 
pigeons  to  be  taken  with  convulsive  seizures  in  which  they  turn 
"cart-wheels"  backwards  at  intervals  until  they  die.  In  the 
acute  type  of  the  disease,  many  birds  sit  with  the  head  greatly 
retracted.  These  symptoms  generally  led  investigators  to  the 
acceptance  of  the  view  that  the  lesions  in  beri-beri  were  prin- 
cipally situated  in  the  nervous  system.  The  studies  of  McCar- 
rison, however,  reveal  the  fact  that  injury  to  the  nerves  is  much 
less  pronounced  than  injury  to  certain  other  tissues. 

On  examining  pigeons  restricted  to  a  diet  of  polished  and  auto- 
claved  rice,  McCarrison  observed  functional  and  degenerative 
changes  in  every  tissue  of  the  body.  The  thymus,  testicles, 
spleen,  ovary,  pancreas,  heart,  liver,  kidneys,  stomach,  thyroid 
and  brain  underwent  atrophy,  the  severity  in  his  cases  being  in 
the  order  named.  The  adrenals  suffered  hypertrophy.  This 
hypertrophy  was  associated  with  a  proportionate  increase  in  the 
content  of  the  glands  in  adrenalin.  Edema,  he  found  to  be  in- 
variably associated  with  hypertrophy  of  the  adrenal  glands. 
In  other  words  edema  seemed  to  be  associated  with  an  excessive 
production  of  adrenalin. 

Inanition  was  found  to  give  rise  to  a  state  of  adrenal  hyper- 
trophy and  to  atrophy  of  other  organs,  the  brain  excepted,  sim- 
ilar to  that  observed  in  birds  fed  solely  upon  polished  rice,  a 
diet  deficient  in  all  known  uncharacterized  food  substances,  very 
deficient  in  protein  and  in  several  essential  inorganic  elements. 

More  serioue  than  nerve  lesions  were  the  gastric,  intestinal, 
biliary  and  pancreatic  disorders  observed  in  birds  as  the  result 
of  a  diet  deficient  in  those  factors  inadequate  in  polished  rice. 
Such  deficient  dietaries  gave  rise  to  congestive  and  atrophic 
changes  in  all  the  coats  of  the  intestine,  especially  the  duodenum ; 
to  lesions  in  its  neuro-muscular  mechanism;  to  impairment  of 
its  digestive  and  assimilative  functions,  and  to  failure  of  its 


228      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

protective  resources  against  bacterial  infection.  In  guinea  pigs 
restricted  to  a  diet  of  oats  and  autoclaved  milk,  there  were  ob- 
served lesions  of  the  digestive  tract  analogous  to  those  seen  in 
pigeons  whose  diet  was  limited  to  polished  rice.  Owing  to  the 
multiple  deficiencies  of  the  rice  diet,  it  is  not  possible  to  decide 
from  these  experiments  as  to  the  specific  effects  of  deficiency  or 
absolute  lack  of  a  single  dietary  component.  It  is  suggestive, 
however,  that  on  a  diet  deficient  only  in  respect  to  the  anti- 
scorbutic substance,  guinea  pigs  developed  lesions,  comparable 
with  those  found  in  birds  with  diets  faulty  in  several  respects. 

McCarrison  (20)  further  studied  upon  pigeons  the  effects  of  a 
diet  of  polished  rice,  butter  fat  and  onions.  This  diet  was  defi- 
cient only  in  the  anti-neuritic  substance  and  in  several  mineral 
elements,  especially  calcium,  phosphorus,  sodium,  chlorin  and 
potassium.  The  iodin  in  the  thyroid  was  probably  sufficient  to 
tide  the  birds  over  the  periods  covered  by  his  experiments.  The 
butter  fat  supplied  the  factor  A;  onions  the  factor  C,  the  anti- 
ophthalmic  and  anti-scorbutic  substances  respectively.  On  this 
diet  typical  symptoms  of  polyneuritis  promptly  appeared,  show- 
ing that  onion  does  not  contain  appreciable  amounts  of  the  anti- 
neuritic  principle.  The  addition  of  onion,  of  which  the  birds 
ate  greedily,  to  polished  rice,  of  which  they  ate  sparingly,  af- 
forded some  measure  of  protection  against  the  damaging  effects 
of  a  diet  of  polished  rice  alone,  for  atrophy  of  the  bowel,  al- 
though often  considerable,  was  usually  less  marked  than  in  birds 
on  the  rice  diet  alone.  Congestion  was  less  prominent,  and  the 
atrophy  of  the  myenteron  and  of  the  elements  of  the  mucosa, 
although  usually  considerable,  were  often  comparatively  slight. 
Two  cases  in  twelve  birds  examined  were  encountered  in  which 
bacterial  infection  of  the  bowel  wall  had  assisted  in  inducing 
profound  deterioration  of  its  structures. 

In  a  considerable  number  of  birds  whose  vitality  was  depleted 
as  the  result  of  the  types  of  faulty  diets  described  by  McCar- 
rison, the  blood  was  found  to  be  infected  by  Bacillus  suipestifer, 
Bacillus  pyocyaneus,  or  another  organism  not  identified.  He 
pointed  out  that  systemic  infection  was  rendered  easier  by  the 
presence  of  the  pathological  processes  existing  in  the  intestine 
as  the  result  of  dietary  deficiencies.  Such  invasion  of  the  body 
was  favored  by  the  impaired  production  of  digestive  juices,  by 
the  malnutrition  of  the  secretory  cells  owing  to  the  continued 
congestion  of  the  mucous  membrane,  by  the  increased  leucocytic 
traffic  in  microorganisms  between  the  mucous  membrane  of  the 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B    229 

intestine  and  the  blood,  by  the  greater  opportunity  which  the 
debilitated  mucous  membrane  provided  for  the  growth  of  micro- 
organisms on  its  surface  and  within  its  substance,  and  to  actual 
breaches  of  continuity  in  the  walls  of  the  bowel  itself.  The 
imperfect  digestion  of  food  in  the  upper  part  of  the  alimentary 
tract  offering  a  favorable  medium  for  the  growth  of  bacteria, 
tended,  by  the  production  of  unwholesome  products,  to  further 
debilitate  the  mucosa,  and  to  increase  the  prospects  of  invasion 
of  the  latter  by  microorganisms.  In  his  experimental  animals 
kept  on  diets  deficient  in  several  factors,  among  which  a  lack  of 
the  anti-neuritic  substance  was  a  prominent  feature,  McCarrison 
observed  with  comparative  frequency  the  superaddition  of  in- 
tense bacterial  invasion  of  the  bowel  walls  upon  the  atrophic  and 
congestive  changes  brought  about  directly  by  malnutrition.  In- 
fection of  the  blood  from  the  bowel  under  such  conditions  would 
be  expected  and  was  repeatedly  demonstrated  by  aerobic  culture 
of  the  heart  blood. 

In  guinea  pigs  restricted  for  a  time  to  a  diet  of  oats  and  auto- 
claved  milk,  McCarrison  also  observed  localized,  destructive 
changes  in  the  mucous  and  underlying  coats  of  the  stomach  and 
duodenum.  These  changes  were  manifest  before  the  animals 
had  developed  any  of  the  characteristic  naked  eye  appearances 
of  scurvy,  and  he  regarded  them  as  pre-scorbutic. 

256.  McCarrison  Points  Out  That  the  Nerve  Lesions  Are 
Less  Severe  Than  Other  Lesions. — This  investigator  further 
pointed  out  that  the  nervous  symptoms  of  polyneuritic  birds 
may  be  rapidly  ameliorated  or  recovered  from  and  yet  these 
birds  may  die  as  the  result  of  the  gastro-intestinal  lesions.  He 
emphasized  that  the  rapid  recovery  from  the  nervous  symptoms 
indicated  that  of  all  the  tissues,  the  nerves  are  least  affected  as 
regards  organic  lesions  by  vitamin  deficiency.  Much  more 
serious  damage  resulted  to  the  intestine,  and  recovery  from  these 
lesions  was  correspondingly  slow.  The  remarkably  rapid  dis- 
appearance of  convulsive  seizures,  of  astasia  and  of  cerebellar 
symptoms,  indicated  clearly  that  specific  fasting  for  the  anti- 
neuritic  substance  was  in  some  manner  intimately  concerned 
with  the  functioning  of  the  nervous  system.  According  to  Mc- 
Carrison, this  may  be  an  activation  or  energizing  action  on  the 
nerve  cells,  or  a  necessary  condition  for  the  completion  of  the 
nervous  current.  Certain  it  is  that  in  the  absence  of  this  sub- 
stance, the  nerve  cells  are  incapable  of  normal  activity,  and 
when  it  is  provided,  normal  functioning  is  reestablished  with 


230      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

dramatic  suddenness.  McCarrison  accepts  the  view,  expressed 
by  Bayliss,  that  the  function  of  the  anti-neuritic  substance  is 
that  of  a  catalyst. 

257.  Subminimal  Provision  of  Uncharacterized  Nutrients 
and  Certain  Diseases  of  Children. — Subminimal  provision  of  the 
uncharacterized  nutrient  principles,  resulting  in  marked  impair- 
ment of  the  neuro-muscular  control  of  the  intestine  with  con- 
sequent failure  of  the  latter  to  transport  its  contents  in  a  nor- 
mal manner,  the  impairment  of  the  assimilative,  secretory  and 
protective  functions,  McCarrison  suggests  as  etiological  factors 
in  certain  pathological  states  in  human  subjects  which  appear 
to  be  the  counterparts  of  these  experimentally  induced  states 
in  animals.  His  views  on  this  subject  are  very  instructive. 

Pigeons  fed  exclusively  on  a  diet  of  polished  rice  frequently 
suffer  from  diarrhea,  and  this  can  be  regarded  as  a  symptom 
of  vitamin  deficiency,  since  it  can  in  many  cases  be  caused  to 
disappear  at  once  by  the  administration  of  alcoholic  extracts 
of  egg  yolks.  Diarrhea  or  colitis  is  almost  a  constant  precursor 
or  concomitant  of  "war  edema,"  which,  as  has  already  been 
shown,  is  in  all  probability,  due  to  the  combined  deficiency  in 
the  diet  of  protein  and  anti-neuritic  substance.  At  least  this 
fact  is  true  in  the  wet  form  of  beri-beri.  Continued  submini- 
mal  dietetic  deficiency  of  certain  sorts  may  lead  to  a  state  of 
chronic  gastro-intestinal  catarrh,  which  characterizes  those  con- 
ditions in  which  mucus  in  abnormal  amounts  is  produced  by 
the  intestine.  Mucous  disease  is  very  common  among  European 
children  in  India  who  are  fed  largely  sterilized  milk,  artificial 
foods,  white  bread,  polished  rice,  poor  butter,  over-cooked  veg- 
etables and  excessive  quantities  of  sugar.  Therapeutic  experi- 
ence has  shown  that  this  malady  yields  to  a  rationally  selected 
dietary.  The  mucous  stools,  the  diarrhea,  the  marked  ifirita- 
bility,  the  unhealthy  appetite  rapidly  disappear  on  such  a  regi- 
men, as  do  also  the  "night  terrors"  from  which  such  children  fre- 
quently suffer  (McCarrison). 

In  the  category  of  syndromes  caused  by  protracted  feeding 
children  on  insufficient  diets,  McCarrison  also  ventures  to  sug- 
gest "celiac  disease,"  described  by  Still  (21).  It  is  thus  char- 
acterized: "Absent  in  breast-fed  children,  its  onset  between  the 
age  of  nine  months  and  two  years,  the  diarrhea  which  so  fre- 
quently precedes  it,  the  cessation  of  growth,  the  ill-formed,  pale, 
'oat-meal  stools/  the  frequent  association  of  scorbutic  symptoms, 
the  abdominal  distention,  the  afebrile  nature  of  the  malady,  the 
diminished  size  of  the  liver,  the  blood  changes,  the  occurrence 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B     231 

of  edema,  the  thin  bones,  the  muscular  feebleness — all  these  find 
their  counterpart  in  pigeons  fed  on  an  exclusive  dietary  of  auto- 
claved  milled  rice." 

Again,  McCarrison  draws  a  parallel  between  the  conditions 
observed  in  animals  restricted  to  faulty  diets  of  the  types  em- 
ployed in  his  experiments  and  the  anatomical  factors  seen  in 
chronic  intestinal  stasis.  Keith  (22)  regards  defective  action 
on  the  part  of  the  abdominal  musculature,  and  a  lesion  of  the 
neuro-muscular  system  of  the  intestine,  as  the  two  factors  of 
primary  importance  in  the  causation  of  this  condition.  Defec- 
tive diet  is  certainly  one  means  by  which  both  the  abdominal 
musculature  and  the  neuro-muscular  system  of  the  intestine  may 
be  simultaneously  impaired  in  functional  capacity. 

It  must  be  kept  in  mind  that  McCarrison  is  hardly  justified  in 
speaking  so  unqualifiedly  of  "vitaminic  deficiency"  as  the  cause 
of  the  lesions  observed.  The  extensive  studies  of  McCollum 
and  Simmonds  and  their  co-workers  have  clearly  shown  the 
serious  consequences  of  deprivation  of  certain  of  the  essential 
mineral  elements,  notably  calcium  and  phosphorus.  McCarri- 
son's  diets  were  almost  without  exception,  greatly  deficient  in 
several  inorganic  elements,  including  calcium,  phosphorus,  so- 
dium and  chlorin,  and  apparently  contained  a  decided  excess  of 
acid  over  basic  radicals.  Deprivation  of  chlorin  quickly  leads 
to  inability  of  the  stomach  to  secrete  hydrochloric  acid,  and 
this  alone  would  seriously  interfere  with  digestion,  and  with  the 
suppression  of  bacterial  growth  in  the  alimentary  tract.  Diets 
deficient  in  mineral  salts  to  the  extent  true  of  a  diet  of  polished 
rice,  of  rice  and  butter,  or  of  rice,  butter  and  onion,  might  well 
lead  to  a  state  of  depletion  of  the  alkali  reserve  in  the  blood. 
Such  deficient  diets  may  account  for  the  air  hunger  which  he 
attributed  to  acidosis  brought  about  by  acid  of  fermentation 
resulting  from  a  diet  too  largely  derived  from  carbohydrate.  It 
is  scarcely  safe  to  attribute  all  the  observed  symptoms  in  his 
experimental  animals  to  deficiency  of  the  uncharacterized  diet- 
ary essentials.  The  conditions  which  he  described  are,  how- 
ever, induced  by  dietaries  of  a  type  which  is  at  the  present  time 
exceedingly  common  in  Europe  and  America.  Putting  aside 
minor  details  which  may  require  revision,  the  conclusions  of 
McCarrison  represent  an  important  advance  in  our  understand- 
ing of  the  relation  between  faulty  nutrition  of  a  certain  type  and 
physical  deterioration. 

258.  McCarrison's  View  of  the  Relation  of  Nuclear  Nutri- 
tion to  Deficiency  Diseases. — McCarrison  regards  the  term 


232     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

"polyneuritis"  as  applied  to  the  morbid  state  resulting  in  pigeons 
from  an  exclusive  dietary  of  autoclaved  rice  as  a  misnomer,  since 
it  suggests  that  the  nervous  tissues  are  exclusively  or  mainly 
involved  in  the  pathological  process,  whereas  no  organ  or  tissue 
escapes  injury  under  such  a  dietary  regimen.  The  glandular 
organs  and  the  organs  of  digestion  are  more  seriously  damaged 
than  is  the  nervous  system.  The  morbid  state  resulting  from 
(among  other  things)  lack  of  what  has  been  called  the  anti- 
neuritic  vitamin,  is  not  in  reality  a  neuritis,  and  the  term  "anti- 
neuritic"  is  inaccurate.  He  regards  the  term  "vitamin"  inapt. 
He  conceives  the  nutrient  principles  in  the  class  which  now  gen- 
erally passes  under  this  term  as  "certainly  nuclear  ingredients 
essential  for  the  nutriment  of  the  living  nucleus.  They  are 
'nuclear  nourishers'  without  which  multiplication  of  cells  does 
not  occur.  The  term  nucleopast  (that  which  feeds  the  nucleus) 
might  well  be  applied  to  them." 

259.  The  Relation  of  Appetite  to  the  Intake  of  Water-Solu- 
ble B. — With  a  view  to  discovering  the  peculiar  role  of  the  anti- 
beri-beri  substance  in  metabolism  Karr  (23)  studied  the  effect 
of  specific  fasting  for  this  substance  upon  the  desire  of  dogs 
to  take  food.    He  fed  diets  which  were  free  from  all  three 
well  recognized  vitamins,  and  which  were  composed  of  isolated 
food  substances,  except  that  commercial  casein  and  wheat  gluten 
were  employed  as  sources  of  protein.    The  dogs  were  restricted 
to  these  diets  until  they  refused  to  take  the  food.    Then  a  source 
of  the  anti-neuritic  factor  was  also  allowed  them,  and  was  fed 
separately.    Yeast,  milk,  tomato,  and  a  concentrated  extract  of 
water-soluble  B  were  employed  for  this  purpose.    It  was  found 
that  the  addition  of  these  substances  to  the  diet  resulted  in 
prompt  response  of  the  appetite,  the  animals  showing  an  in- 
creased desire  for  food.    Karr  concluded  that  there  was  some 
relation  between  the  desire  to  partake  of  food  and  the  amount 
of  water-soluble  B  ingested.    Brewery  yeast  was  found  much 
more  effective  than  bakers'  yeast  for  this  purpose. 

He  further  studied  the  metabolism  of  dogs  deprived  of  water- 
soluble  B,  by  making  quantitative  studies  of  the  assimilation  of 
nitrogen  from  the  alimentary  tract.  No  decrease  in  capacity 
for  digestion,  nor  in  the  character  of  the  metabolic  products 
eliminated  could  be  detected  as  the  result  of  specific  starvation 
for  this  substance. 

260.  We  have  No  Knowledge  of  the  Chemical  Nature  of 
the  Anti-Beri-Beri  Substance. — The  view  of  McCarrison  that 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B     233 

the  anti-neuritic  substance  (his  nucleopast)  is  closely  concerned 
with  the  functioning  of  the  nucleus  would  derive  support  from 
the  early  attempts  of  Funk,  Williams  and  others  to  identify  the 
anti-neuritic  substance  with  purins  or  pyrimidins,  since  these 
are  cleavage  products  of  nucleic  acids.  It  has  been  pointed  out 
how,  in  recent  times,  all  such  views  have  received  a  setback, 
through  failure  of  later  investigators  to  confirm  the  observa- 
tions recorded  with  hydrolytic  products  of  nucleic  acid.  Mc- 
Collum  and  Simmonds  (19)  have  found  thymus  nucleic  acid 
unable  to  replace  in  a  diet,  otherwise  satisfactory,  extracts  which 
contain  the  substance  water-soluble  B,  which  nearly  all  stu- 
dents in  this  field  now  regard  as  identical  with  the  anti-neuritic 
substance.  It  can  hardly  be  regarded  as  satisfactorily  demon- 
strated that  the  so-called  vitamins  are  associated  with  the  nu- 
cleus rather  than  with  some  other  cell  structure. 

261.  Beri-Beri  Does  Not  Appear  in  Fasting  Birds. — Funk 
(24)  made  observation  that  the  symptoms  of  beri-beri  did  not 
appear  in  fasting  birds  and  that  an  increase  in  the  amount  of 
food  ingested,  especially  of  carbohydrate,  hastened  the  onset 
of    the    disease.    Others    have    corroborated    these    findings. 
Butcher  (15)  is  of  the  opinion  that  the  carbohydrate  effect  is 
due  to  an  overloading  of  the  oxidative  mechanism  of  the  body 
rather  than  to  a  specific  relation  between  the  metabolism  of 
carbohydrate  and  "vitamin,"  the  latter  being  used  up  in  the 
process.    Funk  and  Schonborn   (24)   found  an  increased  sugar 
content  in  the  blood  to  result  from  lack  of  the  anti-neuritic  sub- 
stance, and  a  diminished  amount  of  glycogen  in  the  liver. 

262.  Butcher's  Studies  on  Catalase  in  Beri-Beri. — Butcher 
believes  that  the  anti-neuritic  substance  functions  as  a  metabolic 
stimulant.    He  observed   (25)   that  the  body  temperature  fell 
during  the  development  of  avian  polyneuritis  and  rose  after  the 
administration  of  the  anti-neuritic  substance.    Measurement  of 
the  catalase  content  of  the  tissues  of  birds  suffering  from  the 
disease,  revealed  the  fact  that  catalase  is  decreased  to  56  per  cent 
of  the  normal,  and  that  it  returns  to  normal  when  they  are 
treated  with  suitable  extracts  of  natural  foods.    These  findings, 
he  interprets  as  a  great  reduction  in  polyneuritis  of  the  oxida- 
tive processes  of  the  body.     It  is  pointed  out  that  such  a  depres- 
sion of  oxidation  resulted  in  the  accumulation  of  toxic  metabolic 
products,  which  affected  the  nervous  system  and  brought  about 
the  typical  paralysis  and  other  symptoms. 

263.  Glyoxala^e  in  Health  and  in  Experimental  Beri-Beri. 


234      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

— Findlay  (26)  has  reported  a  study  of  the  effect  of  deprivation 
of  pigeons  of  the  anti-beri-beri  substance,  water-soluble  B,  on 
the  content  of  glyoxalase  in  their  tissues.  Glyoxalase  is  an 
enzyme  which  plays  an  important  role  in  the  metabolism  of  car- 
bohydrate. It  has  the  power  to  transform  "glyoxals"  into  lactic 
acid.  The  "glyoxal"  which  serves  in  the  animal  body  as  the 
intermediate  substance  between  glucose  and  lactic  acid  is  known 
as  pyruvic  aldehyd.  Glyoxalase  is  more  abundant  in  the  liver 
than  in  other  tissues. 

Findlay  observed  that  the  amount  of  glyoxalase  in  the  livers 
was  reduced  to  about  half  the  normal  amount  when  the  birds 
were  caused  to  develop  beri-beri  through  restricting  them  to  a 
diet  of  polished  rice.  On  inducing  a  "cure"  by  the  administra- 
tion of  the  anti-neuritic  substance  the  amount  of  glyoxalase 
rose  rapidly  to  two-thirds  of  the  normal  amount  (26). 

264.  Catalase  Studies  Appear  Not  to  Relate  Directly  to  the 
Deficiency  Disease  Problem. — The  studies  made  by  Burge  (26) 
of  the  catalase  content  of  the  tissues  of  several  species  of  ani- 
mals (goose,  pigeon,  sparrow)  indicate,  however,  that  this  may 
vary  in  individuals  of  the  same  species  and  of  similar  weights 
and  in  a  normal  nutritive  condition  by  as  much  as  100  per  cent 
or  more.  It  seems  questionable,  therefore,  whether  one  is  justi- 
fied in  attributing  much  significance  to  change  in  the  catalase 
content  of  the  tissues  of  animals  as  an  index  to  their  capacity  for 
oxidation.  The  fall  in  temperature  is,  perhaps,  but  one  sign  of 
failure  of  the  metabolic  rhythm  caused  by  lack  of  an  indispen- 
sable substance,  just  as  it  may  be  expected  to  fail  when  the  living 
tissues  run  out  of  anything  essential  for  their  proper  functioning. 
According  to  Stehle  (27)  the  variation  in  the  catalase  content  of 
the  blood  and  tissues  is  satisfactorily  explained  as  being  due  to 
variation  in  the  number  of  red  cells  present.  He  regards  this 
test  as  of  no  significance  as  a  measure  of  the  extent  of  biological 
oxidations,  and  expresses  the  view  that  there  is  no  relation  be- 
tween the  latter  and  catalase  values. 

In  the  light  of  these  facts,  it  must  be  admitted  that  we  have 
no  knowledge  whatever  of  the  nature  of  the  role  the  anti-neuritic 
substance  plays  in  metabolism.  We  do  know  that  in  its  absence 
the  metabolic  processes  fail,  and  that  this  failure  involves  not 
primarily  the  nervous  system,  but  all  the  tissues  of  the  body, 
the  brain  and  nerves  being  injured  least  of  all.  The  suggestion 
of  Dutcher,  that  under  conditions  such  as  result  from  specific 
fasting  for  this  substance,  the  accumulation  of  incompletely 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B     235 

metabolized  products,  may  affect  the  nervous  system  and  ac- 
count for  the  striking  loss  of  function,  seems  a  probable  one. 

We  have  already  mentioned  the  fact  that  the  chemical  nature 
of  the  substance  or  substances  lacking  in  the  diets  which  induce 
the  syndrome  generally  designated  as  polyneuritis,  is  entirely 
unknown.  Furthermore,  we  have  no  test  for  its  presence  or 
absence,  other  than  a  properly  planned  feeding  trial  in  which  a 
basal  diet  is  employed  known  to  be  entirely  satisfactory  except 
for  this  one  nutritive  principle.  The  test  animal  is  fed  exclu- 
sively such  a  diet,  to  which  is  added  a  definite  quantity  of  a 
natural  food,  or  of  an  extract  to  be  tested  for  the  anti-neuritic 
factor.  The  success  or  failure  of  the  nutrition  of  the  animal  will 
turn  upon  the  presence  or  absence  in  the  food  or  extract  of  the 
dietary  principle  in  question. 

265.  The  Pigeon  Test  for  the  Anti-neuritic  Substance  Is 
Unsatisfactory. — We  are  now  ready  to  appreciate  the  mislead- 
ing nature  of  the  test  which  many  investigators  have  employed 
in  their  efforts  to  determine  the  relative  values  of  different  food- 
stuffs, or  of  preparations  made  with  the  object  of  isolating  and 
identifying  the  anti-neuritic  substance.  For  this  purpose  the 
procedure  of  Funk  has  been  almost  universally  followed.  This 
consists  of  feeding  pigeons  on  a  dietary  of  polished  rice  until 
acute  symptoms  of  impaired  functional  activity  of  the  nerve  cells 
appear.  The  substance  to  be  tested  is  then  administered  and 
the  recovery  of  the  bird's  powers  of  locomotion  interpreted  to 
indicate  that  the  anti-neuritic  substance  has  been  made  avail- 
able— in  other  words  that  the  test  is  positive.  Failure  of  the 
bird  to  respond  to  this  treatment  is  accepted  as  a  negative  test 
for  this  vitamin. 

It  was  pointed  out  in  1918  by  McCollum  and  Simmonds  (28) 
that  this  test  is  inadequate  and  misleading,  but  no  attention  has 
as  yet  been  paid  by  other  investigators  to  this  criticism  of  the 
classic  "vitamin  test."  At  that  time  they  accepted  the  pre- 
vailing view  that  nerve  degeneration  was  the  most  pronounced 
lesion  in  avian  polyneuritis,  and  emphasized  the  probability 
that  substances  of  a  stimulating  nature  might  whip  up  motor 
nerve  cells  which  had  lost  their  functional  capacity,  and  might 
temporarily  restore  the  birds  to  an  apparently  normal  condition. 
They  pointed  out  the  high  degree  of  improbability  that  so  many 
totally  unrelated  chemical  substances  as  pyrimidins,  purins, 
and  pyridins  could  fulfill  the  same  physiological  role.  They 
were  led  to  suspect  that  the  "curative"  substance  was  not,  in 


236     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

some  cases  at  least,  identical  with  the  indispensable  nutritive 
principle,  essential  for  growth  and  normal  functioning,  but  rather 
bodies  which  possessed  the  pharmacological  property  of  goading 
to  renewed  activity,  nerve  cells  which  had  been  injured  and  had 
ceased  to  functionate.  The  observations  of  Uhlmann  (29)  and 
of  Butcher,  made  later  in  the  same  year,  that  pilocarpin  and 
other  physiological  stimulants  are  actually  able  to  induce  "cures" 
of  pigeons  in  polyneuritis,  supports  this  view.  The  findings  of 
McCarrison,  that  the  nervous  symptoms  in  avian  beri-beri  are 
of  secondary  importance,  further  emphasizes  the  rationality  of 
the  view  that  the  pigeon  test,  as  ordinarily  carried  out,  is  utterly 
without  value  for  the  specific  purpose  for  which  it  has  been  so 
widely  employed. 

266.  Test  for  the  Anti-Beri-Beri  Substance  Proposed  by 
McCollum  and  Simmonds. — McCollum  and  Simmonds  described 
a  test  procedure  which  is  infallible  as  an  indicator  for  the 
presence  or  absence  of  the  anti-neuritic  substance.  The  pro- 
cedure is  to  restrict  young  rats  to  a  diet  consisting  of  purified 
protein,  dextrin,  a  suitable  salt  mixture,  and  butter  fat  or  other 
fat  which  contains  the  factor,  fat-soluble  A.  On  such  a  food 
supply  the  animals  are  unable  to  grow,  and  ultimately  die  with 
or  without  the  development  of  acute  symptoms  characteristic  of 
polyneuritis.  After  a  period  of  two  or  three  weeks  there  is 
added  to  such  a  diet,  a  substance  to  be  tested  for  the  so-called 
anti-neuritic  substance.  If  the  animals  recover  their  normal  nu- 
tritive condition  and  resume  growth,  the  test  is  positive.  If  the 
animals  continue,  however,  to  decline  the  substance  tested  for  is 
absent  from  the  material  under  investigation  or  is  present  in 
amounts  too  small  to  meet  the  nutritive  needs  of  the  subjects 
of  the  test.  It  is  time  that  those  who  are  devoting  their  efforts 
to  the  isolation  and  identification  of  this  most  interesting  sub- 
stance should  adopt  the  above  described  test  with  a  mammal. 
Until  this  is  done  we  may  expect  no  further  progress  in  this 
direction. 

Unfortunately  this  test  requires  moderately  large  amounts  of 
material  of  a  nature  which  it  is  laborious  to  prepare.  Besides 
a  considerable  period  of  time  must  elapse  before  the  outcome  of 
such  test  becomes  apparent.  There  is  no  chemical  test  yet  dis- 
covered which  in  any  way  assists  us  in  following  up  the  physi- 
ologically active  substance  in  our  attempts  to  isolate  it.  Funk 
called  attention  to  the  fact  that  his  active  preparations  (tested 
on  pigeons)  never  failed  to  give  with  the  Folin-Macallum  re- 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B     237 

agent  a  test  for  the  phenol  group  and  Voegtlin  has  extended  the 
use  of  this  reaction  in  his  efforts  to  isolate  the  anti-neuritic  sub- 
stance. This  reaction  is  given  by  proteins,  and  by  a  very  large 
number  of  organic  compounds  which  are  regularly  met  with  in 
biological  work,  and  has,  therefore,  no  specificity,  and  can 
hardly  contribute  toward  progress  in  the  further  investigation  of 
the  problem  of  the  nature  of  this  substance. 

267.  Attempts  to  Employ  Yeast  as  the  Test  Organism  in 
Testing    for    the    Anti-Beri-Beri  Substance.— Williams     (30) 
brought  forward  a  test  for  the  anti-neuritic  principle  which  at 
first  appeared  to  be  a  great  step  in  advance  since  it  promised  to 
detect  very  small  amounts  of  the  substance  in  a  short  space  of 
time  and  with  a  minimal  requirement  of  material.     The  test 
was  based  on  the  conception  that  the  yeast  cell  is  unable  to  grow 
in  a  medium  lacking  in  the  anti-neuritic  substance.    It  was  re- 
ported that  the  growth  was  in  proportion,  roughly,  to  the  amount 
of  "vitamin"  present.    The  test  was  carried  out  with  a  hanging 
drop  of  culture  medium.     The  number  of  progeny  of  a  single 
yeast  cell  counted  after  an  interval  of  a  few  hours  constituted 
the  basis  of  judgment  as  to  the  richness  or  poverty  of  the  solu- 
tion in  the  desired  substance.    Bachmann  (31)  also  described  a 
modification  with  yeast  as  the  test  organism,  and  Funk  (32)  de- 
scribed a  method  for  growing  larger  numbers  of  yeast  cells  and 
measuring  their  volume  by  centrifuging  in  capillary  tubes.    Un- 
fortunately, this  method,  which  was  hailed  with  great  enthusiasm 
when  first  described,  has  proven  to  be  a  complete  disappointment. 

268.  Yeast  Test  Proves  Disappointing. — Souza  and  McCol- 
lum  (33)  attempted  to  make  use  of  yeast  cell  growth  as  a  test 
for  the  anti-neuritic  principle    (water-soluble  B),  and  showed 
that  no  confidence  could  be  placed  in  it.     In  the  first  place,  it 
was  found  that  yeast  could  grow  slowly  in  a  "vitamin"- free  me- 
dium, and  in  the  second  place  that  the  addition  of  extracts  of 
natural  foods  which  had  been  so  treated  as  to  destroy  the  anti- 
neuritic  substance  completely,  were  just  as  effective  in  stimu- 
lating the  growth  of  yeast  as  were  other  extracts  which  did 
contain  the  dietary  principle.     MacDonald  and  McCollum  then 
carried  out  an  extensive  series  of  transplantations  of  pure  cul- 
tures of  yeast  in  a  nutrient  medium  containing  no  trace  of  water- 
soluble  B   (34).     As  a  result  they  showed  conclusively  that  a 
steady  growth,  through  many  successive  seedings,  is  possible  in 
the  absence  of  the  substance  for  which  it  had  been  suggested 
the  growth  of  yeast  could  be  made  a  specific  test.    Fulmer,  Nel- 


238     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

son  and  Sherwood  (35),  almost  simultaneously  published  data 
fully  in  accord  with  that  of  Souza,  MacDonald  and  McCollum, 
and  drew  the  conclusion  that  the  yeast  test  has  no  specificity 
whatever.  We  are,  therefore,  again  thrown  back  upon  the  test 
for  water-soluble  B,  described  by  McCollum  and  Simmonds,  as 
the  only  one  yielding  results  of  any  significance. 

269.  Conclusions. — It  will  be  seen  from  the  description  pre- 
sented in  this  chapter,  that  the  methods  and  results  used  as  a 
basis  of  investigation  and  of  deduction,  have  been  decidedly 
unfruitful  in  the  knowledge  which  they  have  yielded  of  a  food 
substance,  about  the  existence  of  which  there  can  be  no  ques- 
tion, and  which  is  an  indispensable  complex  for  the  living  tissues. 
A  field  of  great  promise  lies  open  here  to  the  investigator,  but 
we  must  wait  until  the  efforts  of  the  future  have  been  directed 
along  lines  more  logical  and  until  investigators  have  viewed  the 
problem  in  its  proper  perspective,  before  we  shall  see  the  success- 
ful solution  of  this  most  interesting  problem. 

In  conclusion  it  appears  that  McCarrison  is  fully  justified  in 
his  view  that  the  condition  commonly  referred  to  as  polyneuritis 
is  actually  not  a  neuritis,  and  the  term  anti-neuritic,  is  not  de- 
scriptive of  the  condition  to  which  it  is  applied.  Degeneration 
of  the  nerves  seems  to  be  one  of  the  later  manifestations  of  the 
lack  of  the  substance  specifically  concerned  with  the  etiology 
of  beri-beri.  It  would  seem  logical  to  discontinue  the  use  of  the 
term  polyneuritis  to  designate  the  experimentally  induced  syn- 
drome. In  the  light  of  McCarrison's  findings  the  term  "experi- 
mental beri-beri"  is  more  fitting  and  proper. 

Since  the  "cure"  affected  in  tests  with  pigeons  is  actually  not 
a  cure,  but  merely  an  alleviation  of  one  of  the  minor  symptoms, 
it  is  obvious  that  the  most  appropriate,  and  most  accurate  con- 
ception of  the  subject  should  center  upon  the  completeness  or 
incompleteness  of  the  diet  with  respect  to  a  substance  on  a 
parity  with  an  indispensable  amino  acid.  The  substance  con- 
cerned with  the  etiology  of  this  syndrome  is  apparently  not  an 
amine  nor  is  it  primarily  anti-neuritic.  While,  for  convenience, 
it  is  permissible  to  employ  the  term  vitamin,  with  the  spelling 
suggested  by  Drummond,  it  is  most  logical  to  use  a  term  which 
has  only  an  algebraic  significance  pending  the  acquisition  of 
further  knowledge  of  the  chemical  nature  of  the  anti-beri-beri 
substance.  For  this  purpose,  the  term  water-soluble  B  appears 
even  more  appropriate,  since  McCarrison  has  published  his 
studies,  than  ever  before. 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B     239 

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1918,  xxxvi,  547. 

Dutcher:  Vitamine  studies,  iii.  Observations  on  the  curative  prop- 
erties of  honey,  nectar,  and  corn  pollen  in  avian  polyneuritis,  Ibid., 
1918,  xxxvi,  551. 

Dutcher:  Vitamine  studies,  iv.  Anti-neuritic  properties  of  certain 
physiological  stimulants,  Ibid.,  1919,  xxxix,  63. 

Uhlmann,  F.:  Contributions  to  the  pharmacology  of  the  vitamines, 
Zeit.  f.  Biol.,  1918,  Ixviii,  419. 

16.  Harden,  and  Zilva:     The  alleged  anti-neuritic  properties  of  a-hydroxy 

pyridines  and  adenine,  Biochem.  Jour.,  1917,  xi,  172. 

17.  Voegtlin,   C.,   and   White,   G.    F.:      Can   adenin   acquire   antineuritic 

properties?,  Jour,  of  Pharm.  and  Exp.  Ther.,  1916,  ix,  155. 

18.  McCollum,  E.  V.,  and  Koch,  M.:     Unpublished  data. 

19.  McCollum,  E.  V.,  and  Simmonds,  N.:     Unpublished  data. 

20.  McCarrison,  R.:     The  pathogenesis  of  deficiency  disease,  Ind.  Jour. 

Med.  Res.,  1919,  vi,  275. 
McCarrison,   R.:      The   effects   of   deprivation   of   B    accessory   food 

factors,  Ibid.,  1919,  vi,  550. 

McCarrison:     Involution  of  the  thymus  in  birds,  Ibid.,  1919,  vi,  557. 
McCarrison:     The   influence   of  dietaries  deficient  in   accessory  food 

factors  in  the  intestine,  Ibid.,  1919,  vii,  167. 
McCarrison:     The  influence  of  a  scorbutic  diet  on  the  adrenal  glands, 

Ibid.,  1919,  vii,  188. 


CHEMICAL  NATURE  OF  WATER-SOLUBLE  B    241 

McCarrison:  The  general  effects  of  deficient  dietaries  on  monkeys, 
Ibid.,  1919,  vii,  308.  [and  24,  1918. 

21.  Still,  F.  G.:     Coeliac  Disease.    Lumleian  Lectures,  Lancet,  Aug.  10,  17, 

22.  Keith,  A.:     The  operative  treatment  of  chronic  intestinal  stasis,  4th 

Ed.'    Edited  by  Sir  W.  Arbuthnot  Lane,  London,  1918. 

23.  Karr,  W.  G.:     Some  effects   of  water-soluble  vitamine  on  nutrition, 

Jour.  Biol.  Chem.,  1920,  xliv,  255. 

Karr:  Metabolism  studies  with  diets  deficient  in  water-soluble  B 
vitamine,  Ibid.,  277. 

24.  Funk,  C.,  and  Douglass,  M.:     Studies  of  beri-beri.    vii.    The  relation- 

ship of  beri-beri  to  glands  of  internal  secretion,  Jour,  of  Physiol., 
1913-14,  xlvii,  475. 

Funk,  C.,  and  Schonborn,  E.:  The  influence  of  a  vitamine-free  diet 
on  the  carbohydrate  metabolism,  Ibid.,  1914,  xlviii,  328. 

25.  Dutcher:      The   nature    and   function   of   the    anti-neuritic   vitamine, 

Proc.  Nat.  Acad.  of  Sci.,  1920,  vi,  10. 

26.  Findlay,  G.  M.:     Glyoxalase  in  avian  beri-beri,  Biochem.  Jour.,  1921, 

xv,  100. 

Burge,  W.  E.,  and  Neill,  A.  J.:  Comparison  of  the  amount  of  catalase 
in  the  muscles  of  large  and  small  animals,  Amer.  Jour.  Physiol., 
1916-17,  xlii,  373. 

27.  Stehle,  R.  L.:     Some  data  concerning  the  alleged  relation  of  catalase 

to  animal  oxidations,  Jour.  Biol.  Chem.,  1919,  xxxix,  403. 

28.  McCollum,  and  Simmonds:     A  study  of  the  dietary  essential  water- 

soluble  B  in  relation  to  its  solubility  and  stability  toward  reagents, 
Jour.  Biol.  Chem.,  1918,  xxxiii,  55. 

29.  Uhlmann,  F.:     Contributions  to  the  pharmacology  of  the  vitamines, 

Zeit.  f.  Biol.,  1918,  Ixviii,  419,  457. 

30.  Williams,    R.   J.:      The    vitamine    requirement    of   yeast.      A    simple 

biological  test  for  vitamine,  Jour.  Biol.  Chem.,  1919,  xxxviii,  465; 
Ibid.,  1920,  xlii,  259. 

31.  Bachmann,  F.  M.:    Vitamine  requirements  of  certain  yeasts,  Jour.  Biol. 

Chem.,  1919,  xxxix,  235. 

32.  Funk,  C.,  and  Dubin,  H.  E.:     A  test  for  beri-beri  vitamine  and  its 

practical  application,  Jour.  Biol.  Chem.,  1920,  xliv,  487. 

33.  Souza,  G.  de  P.,  and  McCollum,  E.  V.:     A  study  of  the  factors  which 

interfere  with  the  use   of  yeast  as  a  test   organism  for  the  anti- 
neuritic  substance,  Jour.  Biol.  Chem.,  1920,  xliv,  113. 

34.  MacDonald,  M.  B.,  and  McCollum,  E.  V.:     The  Bios  of  Wildiers  and 

the  cultivation  of  yeast,  Jour.  Biol.  Chem.,  1921,  xlvi,  525. 

35.  Fulmer,  E.  I.,  Nelson,  V.  E.,  and  Sherwood,  F.  F.:     The  nutritional 

requirements  of  yeast. 

1.  The   role   of  vitamines  in  the   growth  of  yeast,  Jour.   Amer. 

Chem.  Soc.,  1921,  xliii,  186. 

2.  The  effect  of  the  composition  of  the  medium  on  the  growth 

of  yeast,  Ibid.,  191. 

Nelson,  V.  E.,  Fulmer,  E.  I.,  and  Cessna,  R.:  The  synthesis  of  water- 
soluble  B  by  yeast,  Jour.  Biol.  Chem.,  1921,  xlvi,  77. 

36.  Findlay,  G.  M.:     Glyoxalase  in  avian  beri-beri,  Biochem.  Jour.,  1921, 

xv,  104. 

Findlay:  An  experimental  study  of  avian  beri-beri,  Jour,  of  Pathol. 
and  Bact.,  1921,  xxiv,  175. 


CHAPTER  XI 
XEROPHTHALMIA  (KERATOMALACIA) 

270.     The  Necessity  of  a  Fat-Borne  Vitamin  in  the  Diet. — 

In  Chapter  II  it  was  shown  that  it  is  impossible  to  secure  satis- 
factory nutrition  in  the  rat  without  including  in  the  diet  certain 
fats  containing  a  substance  indispensable  for  the  normal  processes 
of  growth  or  for  prolonged  maintenance  of  well-being.  In  the 
light  of  the  history  of  science  the  researches  relating  to  the  ne- 
cessity of  certain  lipins  in  nutrition  are  of  great  interest.  The 
more  significant  investigations  in  this  field  will  now  be  consid- 
ered from  the  standpoint  of  the  present  day  knowledge  of  what 
constitutes  the  normal  diet,  and  emphasis  will  be  laid  upon  the 
relation  of  deficient  diets  to  certain  states  of  malnutrition. 

Stepp  (1)  while  a  student  in  the  laboratory  of  Hofmeister  at 
Strassburg,  performed  the  first  classic  experiment  in  this  field. 
Since  every  animal  and  plant  cell  contains  certain  substances 
having  the  physical  properties  of  fats,  in  addition  to  proteins, 
salts,  carbohydrates  and  water,  to  name  only  the  substances  of 
primary  importance,  Stepp  believed  that  these  fat-like  bodies, 
the  lipins,  must  be  considered  to  be  primary  and  indispensable 
cell  components.  Because  most  food-stuffs  of  animal  or  vege- 
table origin  contain  these  lipins  they  occur  regularly  in  our  diet. 
What  would  happen  if  they  were  eliminated  from  an  otherwise 
adequate  food  mixture?  The  answer  to  this  question  Stepp 
sought  to  obtain  by  a  series  of  experiments  on  mice. 

The  group  of  substances  classified  as  lipins  includes  fats  and 
certain  other  compounds  which  have  more  or  less  similar  physical 
properties.  They  have  a  greasy  feel,  and  are  soluble  in  one 
or  more  of  such  solvents  as  ether,  alcohol,  benzene,  chloroform 
and  acetone.  The  best  known  of  these  lipins  aside  from  ordinary 
fats  are  lecithin,  cholesterol,  phytosterol,  cephalin  and  the 
cerebrosids.  Lecithin  contains  combined  in  its  molecule 
glycerin,  fatty  acid,  phosphoric  acid  and  an  organic  base  called 
cholin.  Cephalin  closely  resembles  lecithin,  but  yields  on 
hydrolysis  a  different  organic  base,  amino  ethyl  alcohol.  Choles- 

242 


XEROPHTHALMIA  (KERATOMALACIA)     243 

terol,  chemically  an  alcohol,  has  certain  physical  resemblances 
to  the  fats.  Cerebrosids  are  compounds  containing  in  their 
molecules  a  fatty  acid,  a  sugar  (galactose)  and  an  organic  base 
(sphingosine).  All  of  these  are  soluble  in  alcohol,  but  they 
differ  in  some  extent  in  their  solubility  in  the  other  solvents 
named.  All  of  these  substances  play  a  prominent  part  in  the 
composition  of  brain  and  nerve  tissue. 

271.  The   Classic    Experiments    of   Stepp    on    Lipin-Free 
Diets. — Stepp  prepared  a  bread  made  from  milk  and  wheat  flour, 
and  another  from  milk  and  "protamol,"  a  protein-rich  prepara- 
tion from  rice.    These  he  extracted  thoroughly  with  alcohol  and 
with  ether.     Mice  were  fed  either  the  extracted  or  the  unex- 
tracted  breads.    Those  fed  the  extracted  food  died  within  thirty 
days,  whereas  those  fed  the  untreated  bread  remained  in  good 
health  during  the  six  or  eight  weeks  they  were  under  observation. 
Stepp  interpreted  these  results  to  mean  that  certain  lipins  (fat- 
like  substances)   are  essential  in  the  diet.     He  next  sought  to 
discover  which  of  the  individual  lipins  was  indispensable  for  the 
maintenance  of  health. 

The  method  employed  was  to  restrict  mice  to  the  lipin-free 
diet  (extracted)  plus  one  or  more  of  the  individual  lipins,  the 
chemistry  of  which  is  more  or  less  well  understood,  and  which 
can  be  prepared  in  a  state  of  purity.  He  tested  out  in  this  way 
lecithin,  cholesterol,  cephalin  and  cerebrosi'ds,  but  in  no  instance 
was  he  successful  in  making  the  extracted  diet  complete  by  the 
addition  of  one  or  more  of  these  purified  substances.  He  also 
made  an  extract  of  egg  yolk  by  shaking  with  cold  alcohol,  and 
divided  the  solution  into  two  portions.  One  of  these  he  heated 
with  95  per  cent  alcohol  for  two  days  in  a  water  bath,  while  the 
other  was  heated  long  enough  to  evaporate  the  alcohol.  Each 
of  these  preparations  was  added  to  a  portion  of  the  extracted 
bread  and  the  two  mixtures  served  as  rations  for  two  groups  of 
mice.  The  group  fed  the  heated  preparation  all  died  within 
thirty  days,  while  the  other  group  receiving  the  unheated  prep- 
aration remained  in  good  health.  Stepp  thus  discovered  that 
the  substances  which  dissolved  from  his  breads  when  they  were 
treated  with  alcohol  and  ether  were  changed  by  heating  during 
several  days,  so  that  they  were  no  longer  capable  of  rendering 
the  extracted  breads  satisfactory  for  the  nutrition  of  mice. 

272.  A  Comparison  of  Birds  with  Mammals  with  Respect 
to  Lipin  Synthesizing  Powers. — Stepp  was  led  by  the  experi- 
ments of  Fingerling  (2)  to  investigate  the  problem  whether  birds 


244     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

differ  from  mammals  in  their  capacity  to  synthesize  the  complex 
lipins.  It  was  shown  by  Fingerling,  and  simultaneously  and 
independently  by  McCollum,  Drescher  and  Halpin  (3)  that 
birds  may  be  satisfactorily  nourished  on  diets  very  poor  in  lipins 
of  every  kind.  McCollum,  Drescher  and  Halpin  fed  three  half- 
grown  hens  exclusively  on  a  mixture  of  polished  rice  and  skim 
milk  powder,  the  latter  having  been  extracted  with  ether  to 
render  it  essentially  free  from  fats.  On  this  diet  the  hens  in- 
creased their  body  weights  about  33  per  cent,  and  laid  57  eggs. 
These  eggs  collectively  contained  82.95  grams  of  lecithin  and 
cephalin.  This  is  several  times  the  amount  of  these  substances 
contained  in  the  entire  tissues  of  the  hens. 

Fingerling  fed  his  ducks  on  a  diet  consisting  of  300  grams 
cooked  potatoes,  80  grams  cooked  blood  albumin,  300  grams  of 
boiled  starch,  10  grams  of  calcium  phosphate  and  10  grams  of 
calcium  carbonate  per  bird  per  day.  The  ducks  had  completed 
their  growth  before  the  beginning  fof  the  experiment.  One  duck 
was  estimated  to  have  deposited  in  her  eggs  302.3  grams  of 
lecithin,  another  246.0  grams  and  another  212.7  grams.  The 
birds  remained  in  good  health  during  the  egg-laying  period. 
This  diet  would  not  have  maintained  them  through  a  second 
laying  period. 

Stepp  (4)  sought  to  determine  whether  pigeons  differ  in  their 
nutritive  requirements  from  mammals.  He  fed  three  pigeons 
exclusively  on  dog  biscuit  which  had  been  very  completely  ex- 
tracted with  hot  alcohol.  All  were  dead  at  the  end  of  43  days. 
The  cause  of  death  was  polyneuritis,  the  analogue  of  beri-beri 
in  man.  Another  pigeon  restricted  to  the  same  food  was  unable 
to  stand  on  the  38th  day  because  of  weakness  and  polyneuritis. 
It  was  then  given  doses  of  a  commercial  "vitamin"  prepara- 
tion (oryphan)  plus  an  alcoholic  extract  of  egg  yolk  to  furnish 
the  lipins  which  Stepp  believed  to  be  indispensable  for  mammals. 
The  bird  rapidly  recovered  and  remained  in  good  condition  on 
this  diet  until  the  92nd  day  of  the  experiment.  It  was  then 
fed  unextracted  dog  biscuit  until  the  98th  day.  The  diet  was 
then  changed  to  extracted  dog  biscuit  supplemented  with  the 
commercial  preparation  of  the  anti-neuritic  substance  (oryphan) 
but  without  the  lipin  extract.  The  body  weight  of  the  bird  at 
this  time  was  271  grams.  It  had  been  observed  on  the  experi- 
mental diets  for  117  days.  On  this  lipin- free  diet  it  steadily, 
but  slowly,  lost  weight  so  that  by  the  193rd  day  it  weighed  but 
217  grams.  It  still  ate  well,  but  its  flight  was  unsteady.  Unex- 


XEROPHTHALMIA  (KERATOMALACIA)  245 

tracted  dog  biscuit  was  fed  for  two  days.  The  pigeon  was  then 
given  the  extracted  dog  biscuit  without  the  addition  of  either 
lipins  or  "vitamin."  The  result  was  a  rapid  loss  in  weight,  and 
the  development  of  symptoms  of  polyneuritis.  Death  occurred 
on  the  233rd  day. 

From  these  observations  Stepp  drew  the  unwarranted  conclu- 
sion that  the  bird  does  not  require  the  indispensable  lipins  or 
substance  which  accompanies  them,  which  he  had  demonstrated 
to  be  necessary  in  the  nutrition  of  mice.  The  steady  loss  of 
weight  of  his  pigeon  when  the  lipin  extract  was  omitted  from 
the  diet  shows  clearly  that  its  nutrition  during  this  part  of  the 
experiment  was  not  satisfactory.  These  results  do  not  warrant 
Stepp's  conclusion  that  there  is  a  difference  in  the  nutritive 
requirements  of  birds  and  mammals. 

273.  Element  of  Growth  Was  Not  Included  in  Stepp's  Ex- 
periments.— It  should  be  remembered  that  in  Stepp's  investiga- 
tions the  element  of  growth  was  not  included.  He  studied  the 
nutritive  requirements  for  maintenance  of  mice  and  pigeons, 
whose  growth  was  complete.  His  results  are,  nevertheless,  of 
great  interest  because  they  agree  with  those  McCollum  and 
Davis  obtained  with  growing  rats  (5).  They  established  the 
fact  that  for  the  mouse  and  rat,  two  substances  at  least,  other 
than  the  conventional  components  of  the  diet,  protein,  fat,  carbo- 
hydrate and  salts,  are  essential  for  satisfactory  nutrition.  Stepp, 
in  his  early  studies,  interpreted  the  results  to  indicate  that  only 
certain  lipins  were  necessary  to  supplement  successfully  a  diet 
of  purified  food  substances  of  the  hitherto  recognized  group. 
When  Funk  demonstrated  the  necessity  of  a  protective  "vitamin" 
for  the  prevention  of  beri-beri,  Stepp  extended  his  studies  to 
include  "vitamins"  in  addition  to  lipins.  Finally,  in  November, 
1915,  he  presented  data  showing  the  necessity  of  "vitamins" 
as  well  as  certain  other  substances  soluble  in  alcohol  (6) .  These 
are  present  in  many  natural  foods.  McCollum  and  Davis  simul- 
taneously published  a  paper  in  which  they  demonstrated  the 
necessity  for  growth  in  rats,  of  a  fat-soluble  and  a  water-soluble 
substance.  It  may  be  well  at  this  point  to  call  attention  to  the 
bearing  of  the  studies  of  Stepp  on  the  question  whether  there 
are  any  demonstrated  differences  in  the  nutritive  requirements 
of  mammals  during  growth  as  contrasted  with  those  for  main- 
tenance in  the  adult. 

274.     Drummond's  View  That  Fat-Soluble  A  Is  Not  Neces- 
sary for  Maintenance  in  the  Adult.— Drummond  (7)  holds  the 


246      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

view  that  adult  rats  need  little  if  any  of  the  dietary  factor,  fat- 
soluble  A,  for  the  maintenance  of  health.  Stepp's  observations 
indicate  the  reverse.  McCollum  and  Simmonds  (8)  found,  when 
the  sole  source  of  fat-soluble  A  was  33  per  cent  of  millet  seed 
in  the  food  mixture,  adult  rats  developed,  after  60  days,  severe 
xerophthalmia,  although  this  seed  contains  demonstrable  amounts 
of  this  dietary  essential.  It  is  possible  that  adults  require  some- 
what less  of  this  factor  for  normal  maintenance  than  young 
animals  do  for  growth,  but  this  fact  does  not  appear  to  have 
been  proven.  It  is  important  to  appreciate  that  an  animal  on 
a  diet  which  is  highly  satisfactory  in  all  respects  other  than  in 
its  content  of  fat-soluble  A,  will  not  show  distinct  signs  of  a 
lack  of  this  substance  for  a  much  longer  time  than  would  be 
necessary  to  make  the  shortage  apparent  if  a  second  factor  in 
the  diet  were  below  the  optimum  in  quality  and  quantity.  The 
extent  to  which  this  second  factor  deviates  from  the  optimum 
would  determine  the  reaction  of  the  animal,  whether  it  would 
be  prompt,  or  delayed  in  showing  the  effects  of  faulty  nutrition. 
If  at  the  same  time  there  should  exist  a  deficiency  in  a  third 
factor,  the  effects  of  lack  of  fat-soluble  A  would  become  in- 
creasingly apparent.  In  the  interpretation  of  quality  in  diet 
it  is  of  the  utmost  importance  to  realize  that  there  is  an  inter- 
relation of  factors,  and  that  it  is  easily  possible  to  overlook,  in 
short  experiments,  deficiencies  which  are  of  small  magnitude, 
but  which,  nevertheless,  manifest  themselves  sooner  or  later  in 
the  life  history  of  the  individual. 

Nearly  all  investigators  in  the  field  of  nutrition  have  now 
accepted  the  view  first  formulated  by  McCollum  and  Davis  (5) 
that  two  classes  of  unknown  substances  are  necessary  for  the 
normal  nutrition  of  the  rat.  The  terminology  by  which  McCol- 
lum and  Kennedy  (9)  designated  these  as  fat-soluble  A  and 
water-soluble  B,  has  been  widely  adopted,  because  of  its  con- 
venience, and  because  of  the  desirability  of  using  algebraic 
terms  to  designate  the  substances  in  question  until  further  in- 
vestigations reveal  their  chemical  nature.  F.  Rohmann,  of 
Breslau,  who  has  for  many  years  studied  the  problem  of  nour- 
ishing mice  on  diets  composed  of  partially  purified  food  sub- 
stances, refuses  to  accept  the  idea  that  there  are  any  essential 
components  of  the  diet  which  cannot  be  furnished  by  purified 
proteins,  carbohydrates,  fats  and  mineral  salts,  provided  the 
proteins  contained  in  the  diet  have  an  appropriate  chemical 
constitution  (10). 


XEROPHTHALMIA  (KERATOMALACIA)  247 

275.  The   Experiments  of   McArthur   and   Luckett. — Mc- 
Arthur and  Luckett  (11)  misjudged  as  did  Stepp  in  his  earlier 
experiments,  the  peculiar   nutritive   value  of  butter   fat   as   a 
source  of  an  unidentified  dietary  essential.     Stepp   (12)   added 
butter  fat  to  a  diet  free  from  substances  soluble  in  ether  and 
alcohol,  and  observed  that  the  mice  in  his  experiments  died  just 
as  early  as  they  did  on  the  lipin-free  diet,  whereas  the  same 
ration  was  made  adequate  by  the  addition  of  an  alcoholic  ex- 
tract of  egg  yolk  or  calf  brain.    McArthur  and  Luckett  did  like- 
wise.   These  investigators,  like  Stepp,  drew  the  conclusion  that 
butter  does  not  contain  an  indispensable  substance  for  the  nutri- 
tion of  the  mouse.    The  explanation  of  their  results  was  finally 
brought  out  by  the  studies  of  McCollum  and  Davis  (5).    When 
butter  fat  or  an  ether  extract  of  egg  yolk  was  added  to  a  diet 
of  purified   food-stuffs,   only   one   of  the   unidentified   dietary 
essentials   (fat-soluble  A)   was  introduced.    When  an  alcoholic 
extract  of  egg  yolk  was  added,  both  fat-soluble  A  and  water- 
soluble  B  were  contained  in  the  added  material.    Since  the  addi- 
tion of  either  the  factors  A  or  B  alone  does  not  make  a  diet  of 
purified  protein,  carbohydrate,  fat  and  mineral  salts  complete, 
the  animals  fed  such  diets  with  but  one  addition  died,  and  there 
was  no  evidence  in  the  experiment  to  show  that  the  butter  fat 
had  any  special  properties.    It  was  difficult  to  discover  that  in 
the  one  procedure  one  essential  substance,  and  in  the  other  two, 
were  being  added,  and  that  the  presence  of  the  two  was  the 
determining  factor  in  the  outcome  of  the  experiment. 

276.  Symptoms    Resulting   from    Specific    Starvation    for 
Fat-Soluble  A. — When  animals  are  restricted  to  a  diet  lacking 
in  fat-soluble  A,  there  develops  after  a  few  weeks  a  peculiar 
pathological  condition  of  the  eyes  which  is  so  characteristic  that 
it  must  be  regarded  as  one  of  the  manifestations  of  a  specific 
syndrome.    It  has  not  yet  received  from  pathologists  the  atten- 
tion it  deserves.    In  1909  Knapp  (13)  restricted  rats  to  a  diet 
of  isolated  and  purified  food  substances,  consisting  of  proteins, 
carbohydrates,  fats  and  mineral  salts,  and  described  a  severe 
conjunctivitis  which  developed  as  the  nutrition  of  his  animals 
failed.     In  other  experiments  lecithin,  cholesterol  and  nucleic 
acid  were  added  to  the  basal  diet,  and  although  the  animals 
suffered  from  malnutrition  and  died,  the  characteristic  eye  symp- 
toms did  not  appear.    This  is  probably  to  be  explained  by  the 
presence  of  fat-soluble  A  as  an  impurity  in  the  lipins  which  he 
employed  as  additions  to  the  experimental  diet. 


248     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Freise,  Goldschmidt  and  Frank  (14),  in  1913  observed  the 
same  eye  disorder  in  their  experiments  with  rats  which  they  re- 
stricted to  a  diet  similar  to  that  used  by  Knapp.  They  described 
the  condition  in  more  detail  than  did  Knapp.  They  stated  that 
in  about  three  weeks  from  the  beginning  of  the  experiment  the 
eyelashes  of  the  animals  began  to  fall  out.  There  was  also  a 
retraction  of  the  eyeballs  from  spasm  of  the  extrinsic  muscles  of 
the  eyes.  In  five  to  six  weeks  the  sclerotic  coat  became  dry,  the 
cornea  clouded  and  finally  ulcerous,  but  without  marked  in- 
flammation. The  fur  of  the  animals  became  rough.  They  suc- 
cumbed to  malnutrition,  and  histological  examination  of  the 
sclerotic  coat  revealed  the  typical  picture  of  keratomalacia  as  it 
is  seen  in  man.  In  cases  where  the  ulceration  of  the  sclera  of 
one  eye  was  well  developed,  and  was  beginning  to  show  in  the 
other,  the  process  could  be  entirely  arrested  by  the  administra- 
tion, suggested  by  the  work  of  Hopkins,  of  two  cubic  centimeters 
of  skim  milk  per  day.  These  workers  believed  that  the  condi- 
tion developed  only  in  young  growing  animals,  and  that  it  was 
closely  related  to  the  phenomena  of  growth.  They  attributed 
the  condition  to  lack  of  "accessory"  substances  in  the  diet. 

277.  Hopkins  Experiments  Demonstrating  the  Necessity 
of  "Accessory"  Food  Substances. — When  Hopkins  pointed  out 
in  1912  that  the  addition  of  small  amounts  of  milk  to  a  diet  of 
purified  food  substances  would  lead  to  growth,  whereas  without 
such  addition  the  animals  failed,  and  on  the  basis  of  this  ob- 
servation conceived  the  idea  that  certain  "accessory"  food  sub- 
stances are  necessary  in  the  diet,  he  had  no  comprehension, 
apparently,  of  the  number  or  specificity  of  these  substances. 
This  view  did  not  become  appreciated  until  Funk  attributed  to 
specific   deficiency   a  number  of  diseases,   especially   beri-beri, 
scurvy,  pellagra,  rickets  and  sprue,  and  expressed  the  belief  that 
a  special  "vitamin"  for  growth  was  essential.     The  view  that 
there  were  two  unidentified  substances  essential  in  the  diet  did 
not  become  established  on  experimental  evidence  until  McCollum 
and  Davis   (5)  in  1915  published  their  paper  on  the  essential 
factors  in  the  diet  during  growth. 

278.  Osborne  and  Mendel  Describe  Ophthalmia  in  Their 
Experimental  Rats. — In  1913  Osborne  and  Mendel  (15)  called 
attention  to  the  prevalence  of  an  inflammation  of  the  eyes  of 
their  rats  restricted  to  a  diet  of  purified  proteins,  "protein-free 
milk,"  lard  and  starch.     They  referred  to  this  as  a  "type  of 
nutritive  deficiency  exemplified  in  the  form  of  an  infectious  eye 


XEROPHTHALMIA  (KERATOMALACIA)     249 

disease  prevalent  in  animals  inappropriately  fed,"  and  stated 
that  the  condition  was  speedily  alleviated  by  the  introduction 
of  butter- fat  into  the  diet. 

279.  McCollum  and  Simrrionds  Prove  Xerophthalmia  to  be 
Due  Specifically  to  Lack  of  Fat-Soluble  A. — McCollum  and 
Simmonds  had  repeatedly  observed  the  development  of  this  pecu- 
liar form  of  ophthalmia  in  animals  subjected  to  their  experimen- 
tal diets.    They,  however,  did  not  feel  convinced  until  they  had 
collected  numerous  observations,  all  of  which  pointed  to  the 
belief  that  the  eye  disease  in  question  is  non-infectious,  that  it 
could  more  satisfactorily  be  explained  on  the  basis  of  specific 
starvation  for  fat-soluble  A,  than  on  any  other.    Many  groups 
of  rats  in  various  degrees  of  enfeeblement  or  arrested  develop- 
ment resulting  from  restriction  to  faulty  diets  of  various  types, 
failed  to  develop  the  disease,  when  others  in  adjacent  cages  were 
suffering  from  it.    They  found  it  to  occur  only  in  those  animals 
whose  diets  were  faulty  in  the  content  of  fat-soluble  A.     Mc- 
Collum and  Simmonds    (16)    correlated  these  observations  on 
rats  with  those  reported  by  Bloch  and  by  Mori,  and  came  to 
the  conclusion  that  the  xerophthalmia  or  keratomalacia  pro- 
duced experimentally  in  animals  is  the  analogue  of  the  condition 
which  these  authors  have  reported  in  man.    It  was  on  evidence 
of  that  nature  that  they  formulated  the  view  that  this  type  of 
xerophthalmia  is  a  deficiency  disease  in  the  same  sense  as  beri- 
beri, and  that  it  is  due  specifically  to  lack  of  fat-soluble  A. 

280.  Mori  Described  Ophthalmia  of  Dietary  Origin  in  Man 
as  Early  as  1904. — The  observations  of  Mori   (17)   mentioned 
above  refer  to  about  fourteen  hundred  cases  of  xerophthalmia 
among  children  between  the  ages  of  two  and  five  years,  which 
occurred    in    Japan    in    1905-1907.     These    children    exhibited 
keratomalacia  as  well  as  xerosis  of  the  conjunctiva.    This  syn- 
drome is  known  in  Japan  as  hikan.    Mori  states  that  the  disease 
does  not  occur  among  fisher  folk,  but  among  people  whose  diet 
is  largely  of  vegetable  origin.    The  children  suffered  from  diar- 
rhea in  the  summer  time  in  addition  to  the  eye  lesion.    The  diet 
consisted  of  "rice,  barley,  cereals,  beans  and  other  vegetables." 
The  nature  of  the  other  vegetables  and  the  relative  amounts 
of  the  different  articles  in  the  diet  were  not  stated.     Prompt 
relief  of  the  eye  symptoms  was  observed  when  cod  liver  oil  was 
administered.     Chicken  livers  and  eel  fat  were  also  found  to 
be  effective  as  a  remedy.    The  successful  treatment  of  xeroph- 
thalmia in  these  children  by  the  administration  of  cod  liver  oil, 


250     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

or  by  the  feeding  of  a  glandular  organ,  such  as  liver,  affords  very 
strong  evidence  that  the  ophthalmia  was  the  same  condition  as 
has  been  produced  experimentally  in  animals,  since  it  is  relieved 
by  the  addition  to  the  diet  of  fat-soluble  A. 

281.  Bloch  Adds  Greatly  to  Our  Knowledge  of  Ophthalmia 
of  Dietary  Origin  in  Infants. — Bloch  (18)  described  fifty  cases 
of  xerophthalmia  in  children  in  the  vicinity  of  Copenhagen  that 
occurred  during  the  years  1912-16.  Most  cases  were  infants 
under  one  year  of  age.  They  were  suffering  from  severe  mal- 
nutrition. The  skin  was  dry,  shriveled  and  scaly.  Their  diet 
consisted  of  separator  skim  milk,  which  was  therefore  prac- 
tically free  from  fat.  This  milk  had  been  pasteurized  and  then 
cooked  again  in  the  home  before  it  was  fed.  Oatmeal  gruel  and 
barley  soup  constituted  the  other  important  ingredients  of  the 
diet.  These  infants  were  doubtless  suffering  from  a  complica- 
tion of  faulty  dietary  factors.  Such  a  diet  would  contain  rela- 
tively little  fat-soluble  A,  the  amount  depending  on  the  nature 
of  the  feed  of  the  cows;  the  thoroughness  of  skimming;  the 
amount  of  skim  milk  which  was  consumed  by  the  infants,  and 
the  extent  to  which  the  heat  treatment  destroyed  it.  If  the 
consumption  of  cereal  was  large,  the  amount  of  milk  taken 
would  be  too  small  to  insure  a  satisfactory  inorganic  content 
in  the  diet.  Such  a  diet  as  Bloch  describes  would  be  practically 
free  from  anti-scorbutic  substance.  The  infants  which  he  ob- 
served may  well  have  been  borderline  cases  of  both  scurvy  and 
beri-beri  as  well  as  well  developed  cases  of  xerophthalmia.  In 
the  past  we  have  failed  to  appreciate  the  seriousness  of  the 
condition  of  malnutrition  which  falls  but  little  short  of  a  defi- 
ciency disease.  The  effects  on  vitality  may  be  very  pronounced 
in  cases  where  a  faulty  diet  is  persisted  in  to  a  point  where 
clinically  observable  symptoms  are  about  ready  to  appear,  but 
while  no  clear  cut  lesions  are  detectable. 

Bloch  referred  the  malnutrition  in  these  infants  to  lack  of  fat 
in  the  diet,  basing  his  belief  on  the  observation  that  the  eye 
trouble  could  be  relieved  by  the  administration  of  cod  liver  oil, 
whole  milk  or  cream  mixtures.  In  a  sense  he  was  right,  but  in 
the  light  of  our  present  knowledge  concerning  the  differences  in 
the  dietary  properties  of  various  fats,  there  is  no  reasonable 
doubt  that  vegetable  fats  such  as  olive  oil,  cotton-seed  oil,  soy 
bean  oil,  cocoanut  oil,  etc.,  would  not  have  been  of  any  therapeu- 
tic value.  The  prominence  of  skim  milk  suggested  to  Bloch  the 
paucity  of  fat  in  the  diet,  and  he  fortunately  chose  two  effective 


XEROPHTHALMIA  (KERATOMALACIA)  251 

fats,  cod  liver  oil  and  butter  fat,  for  administration  to  his  infants. 
His  generalization  from  the  effect  of  these  fats,  to  fats  in  gen- 
eral, was,  we  now  appreciate,  unwarranted. 

282.  Ophthalmia  in  Infants  Generally  Complicated  with 
Scurvy  or  Other  Deficiency  Syndrome. — Malnutrition  of  a 
specific  type  rarely,  if  ever,  occurs  uncomplicated  in  man  or 
animals  living  on  a  diet  of  ordinary  food-stuffs,  even  when  the 
list  of  foods  available  is  greatly  restricted  and  the  diet  unsatis- 
factory to  a  pronounced  degree.  The  specific  deficiency  dis- 
eases, with  the  possible  exception  of  scurvy,  can  be  produced  as 
uncomplicated  syndromes,  only  by  carefully  planned  experi- 
mental diets.  This  will  be  evident  to  one  who  considers  the  na- 
ture of  the  deficiencies  of  polished  rice  and  of  muscle  meats,  the 
prominent  articles  in  the  diet  of  those  peoples  in  certain  coun- 
tries, who  suffer  most  from  beri-beri.  Such  a  diet  is  deficient  in 
mineral  elements  to  a  degree  that  would  in  time  greatly  lower 
the  vitality  and  shorten  life.  Its  content  of  fat-soluble  A  is  so 
low  as  to  produce  a  borderline,  if  not  an  actual  condition  of 
keratomalacia.  The  defect  which  produces  the  most  prompt 
and  most  visible  pathological  picture  is  that  resulting  from  the 
lack  of  the  anti-neuritic  substance.  Beri-beri  appears,  and  over- 
shadows in  the  eyes  of  observers,  all  other  features  of  general 
malnutrition. 

In  the  reported  cases  of  xerophthalmia  in  man,  the  inference 
seems  justified  that,  although  many  of  the  infants  were  doubt- 
less suffering  from  latent  scurvy  and  under- feeding,  lack  of  suffi- 
cient fat-soluble  A  was  a  prominent  factor  in  their  malnutrition. 

283.  Hess  and  Unger  Express  the  View  That  Fat-Soluble  A 
Is  Not  Very  Important  in  Human  Nutrition. — Hess  and  Unger 
(19)  hold  the  view  that  in  human  nutrition  there  is  not  likely 
to  be  a  deficiency  of  fat-soluble  A  sufficiently  pronounced  to  be 
a  factor  of  importance  except  under  exceptional  circumstances — 
as  in  times  of  war.  They  base  their  conclusion  on  an  experiment 
conducted  with  five  infants  who  were  fed  dried  skimmed  milk 
(Krystalak)  180  grams;  sucrose  30  grams;  cotton-seed  oil  30 
c.c.;  autolyzed  yeast  15-30  c.c.;  orange  juice  and  cereal.  The 
autolyzed  yeast  was  to  insure  a  liberal  supply  of  the  anti- 
neuritic  substance,  water-soluble  B.  The  orange  juice  was  to 
supply  the  anti-scorbutic  factor,  water-soluble  C,  and  the  olive 
oil  to  furnish  fat.  The  diet  was  assumed  to  be  almost  free  from 
fat-soluble  A,  but  entirely  adequate  so  far  as  definite  under- 
standing of  the  necessary  factors  can  be  judged  in  the  light  of 


252     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

present  knowledge.  The  babies  were  from  four  to  nine  months 
old.  They  were  confined  to  this  diet  for  periods  varying  from 
five  to  nine  months.  Rickets  was  not  observed  in  any  of  the 
babies.  In  fact  they  grew  in  a  fairly  normal  manner.  From 
this  experimental  data  Hess  and  Unger  were  led  to  doubt 
whether  more  than  traces  of  fat-soluble  A  are  necessary  in  the 
nutrition  of  the  human  infant  when  other  factors  in  the  diet  are 
satisfactory. 

There  is  a  fundamental  weakness  in  their  experiment.  The 
assumption  that  the  diet  employed  was  nearly  devoid  of  fat- 
soluble  A,  the  factor  on  which  the  results  were  supposed  to  turn, 
is  erroneous.  Soon  after  the  discovery  of  the  existence  of  this 
dietary  factor,  McCollum  and  Davis  (20)  studied  the  relative 
values  of  the  fat  and  non-fat  portion  of  milk  as  sources  of  fat- 
soluble  A.  They  compared  the  growth  of  young  rats  fed  on 
diets  of  similar  composition  with  respect  to  the  several  com- 
ponents. They  made  3  per  cent  of  butter  fat  the  sole  source  of 
fat-soluble  A  in  one  diet  and  10  per  cent  of  skimmed  milk  powder 
(Merrell-Soule)  in  another.  It  was  observed  that  growth  and 
well-being  were  about  equally  well  maintained  in  the  two  groups 
of  animals.  In  100  c.c.  of  whole  milk  there  is  approximately  3 
grams  of  fat  and  10  grams  of  solids  not  fat,  and  in  the  skimmed 
milk  powder  the  fat  was  not  more  than  0.6  per  cent.  The  10 
per  cent  of  skimmed  milk  powder  used  in  the  one  experiment, 
therefore,  represented  the  same  amount  of  milk  as  did  the  3  per 
cent  of  butter  fat.  From  this  observation  McCollum  and  Davis 
drew  the  conclusion  that  skimmed  milk  contains  much  more  fat- 
soluble  A  than  could  be  accounted  for  on  the  basis  of  its  fat 
content.  They  expressed  their  belief  that  about  half  the  fat- 
soluble  A  contained  in  milk  is  removed  with  the  butter  fat  in 
skimming  with  the  centrifugal  separator,  and  half  remains  be- 
hind in  the  skimmed  milk.  If  this  observation  is  trustworthy, 
the  diet  employed  by  Hess  and  Unger  was  not  very  deficient  in 
fat-soluble  A,  and  indeed  did  for  their  infants  just  what  it  would 
have  done  for  the  nutrition  of  young  rats — animals  which  re- 
spond very  sensitively  to  a  deficiency  of  this  substance.  Hop- 
kins (21)  has  recently  stated  in  a  symposium  on  diet  held  by 
the  British  Medical  Association,  that  he  has  observed  experi- 
mentally the  effects  of  skimmed  milk  as  a  source  of  fat-soluble 
A,  and  is  also  convinced  that  it  contains  much  more  of  this 

284.  Urinary  Calculi  in  Relation  to  Deficiency  of  Fat-Solu- 
substance  than  its  fat  content  would  lead  one  to  expect. 


XEROPHTHALMIA  (KERATOMALACIA)  253 

ble  A. — A  further  abnormality  attributed  to  deficiency  of  fat- 
soluble  A  in  the  diet  was  reported  by  Osborne  and  Mendel  (22). 
They  found  in  the  urinary  tract,  calculi  of  calcium  phosphate. 
In  857  autopsies  they  found  calculi  in  91  animals.  Forty-three 
per  cent  of  these  had  not  had  a  satisfactory  supply  of  fat-soluble 
A.  Mendel  (23)  calls  attention  to  the  fact  that  urinary  calculi 
are  exceptionally  common  among  peoples  of  the  Tropics,  and  of 
the  Far  East,  who  live  on  diets  quite  unlike  the  mixed  diets 
common  among  Europeans  and  Americans.  He  suggests  a  corre- 
lation of  his  experience  with  the  well-known  fact  that  these 
calculi  are  deposited  from  neutral  or  alkaline  urines,  which  fre- 
quently owe  their  reaction  to  the  formation  of  ammonia  as  a 
result  of  bacterial  decomposition.  The  possibility  that  the  in- 
vasion of  the  urinary  tract  by  microorganisms  results  from  the 
lowered  vitality  due  to  partial  or  complete  starvation  for  fat- 
soluble  A  is  suggested  by  their  findings  at  necropsy.  I  am  not 
greatly  impressed  with  the  view  that  there  is  any  specific  rela- 
tion between  starvation  for  fat-soluble  A  and  the  occurrence  of 
calculi.  Fifty-seven  per  cent  of  the  animals  found  in  the 
autopsies  of  Osborne  and  Mendel  to  contain  calculi  of  the 
urinary  tract  had  had  a  satisfactory  supply  of  this  dietary 
factor.  In  our  own  experience  calculi  have  occurred  so  fre- 
quently in  animals  whose  diets  contained  an  abundance  of  this 
factor,  but  were  faulty  in  other  respects,  that  it  would  seem  to 
be  the  result  of  general  debility  rather  than  lowered  vitality 
brought  about  by  specific  cause. 

285.  Hemeralopia  and  Nyctalopia  Possibly  Associated  with 
Vitamin  Deficiency. — It  is  of  interest  in  this  connection  to  call 
attention  to  another  widespread  condition  which  seems  related 
to  a  deficiency  of  fat-soluble  A  in  the  diet  of  man.  Hemeralopia, 
or  inability  to  see  by  subdued  light,  is  common  in  several  parts 
of  the  world,  and  has  been  frequently  referred  to  faulty  nutri- 
tion. Thus  Krienes  (24)  attributed  certain  cases  of  the  disease 
to  malnutrition.  De  Gouvea  (25)  gave  a  resume  of  the  literature 
of  the  subject  up  to  1883,  and  described  many  cases  of  hemer- 
alopia  among  the  negro  slaves  who  worked  on  the  coffee  planta- 
tions of  San  Paulo,  Brazil.  They  were  restricted  to  a  diet  of 
beans,  pork  fat  and  maize  meal.  Slaves  on  other  plantations 
who  were  better  fed  did  not  suffer  from  the  disease.  Little  (26) 
mentioned  the  prevalence  of  night  blindness  (nyctalopia,  often 
inaccurately  called  hemeralopia)  among  the  people  of  New- 
foundland. He  also  stated  that  the  diet  was  sufficiently  poor 


254      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

to  make  beri-beri  and  scurvy  a  common  occurrence.  I  am 
informed  by  Dr.  Grenfell  that  night-blindness  is  common  in 
Labrador.  Dr.  Appleton,  in  a  private  communication  also  in- 
forms me  that  she  has  seen  many  cases  of  this  eye  disease  in 
Newfoundland  and  Labrador.  The  diet  of  the  inhabitants  of 
these  regions  consists  almost  exclusively  of  bread  made  from 
bolted  wheat  flour,  canned  meats,  fish,  molasses,  tea  and  small 
amounts  of  raisins. 

The  diet  of  these  regions  is  of  a  character  which  one  would 
expect  to  be  dangerously  low  in  its  content  of  fat-soluble  A  as 
well  as  deficient  in  other  respects.  It  is  essentially  a  diet  de- 
rived from  the  endosperm  of  wheat,  muscle  tissue  of  beef,  pork 
and  fish,  and  molasses.  The  last  article  of  food,  after  its  drastic 
treatment  in  the  manufacture  of  sugar,  would  not  be  expected 
to  have  any  appreciable  value  as  a  source  of  any  of  the -uni- 
dentified dietary  factors.  Such  a  diet  is  actually  so  poor  in 
the  anti-neuritic  substance  that  beri-beri  is  of  frequent  occur- 
rence, and  is  likewise  so  poor  in  the  anti-scorbutic  factor  as  to 
make  scurvy  common.  Judging  from  the  known  dietary  prop- 
erties of  muscle  meats,  there  is  every  reason  to  believe  that  the 
diet  is  also  deficient  in  fat-soluble  A.  The  regular  use  of  cod 
livers  as  an  adjuvant  to  the  diet  in  these  places  is  advisable, 
since  this  would  prevent  both  beri-beri  and  scurvy,  and  perhaps 
also  night-blindness. 

Dr.  Ann  Young,  who  has  had  experience  as  a  medical  mis- 
sionary in  India,  has  informed  me  that  night-blindness  is  com- 
mon in  the  vicinity  of  Calcutta  (27).  The  popular  remedy  for 
the  condition  consists  in  poulticing  the  eyes  with  an  exudate  of 
fresh  goat's  liver  and  in  including  liver  in  the  food.  I  have  also 
been  informed  from  several  sources  that  the  value  of  liver  for 
the  cure  of  night-blindness  has  been  appreciated  in  Japan  from 
very  early  times.  It  has  already  been  pointed  out  that  the 
glandular  organs  of  animals  are  good  sources  of  fat-soluble  A. 
It  is  not  to  be  wondered  at,  if  our  surmise  is  correct,  that  night- 
blindness  in  certain  parts  of  the  world  is  in  reality  due  to  specific 
starvation  for  fat-soluble  A.  That  it  should  occur  in  parts  of 
India  where  the  people  subsist  to  a  great  extent  on  a  diet  de- 
rived from  muscle  meats  and  from  those  parts  of  the  plants 
functionating  as  storage  tissues  is  to  be  expected  from  our  present 
knowledge  of  nutrition.  Several  types  of  faults  in  such  diets 
would  tend  to  predispose  to  susceptibility  to  lack  of  fat-soluble 
A.  In  Japan  where  there  is  no  dairy  industry,  the  supply  of 


XEROPHTHALMIA  (KERATOMALACIA)  255 

fat-soluble  A  would  depend  largely  upon  the  extent  to  which 
leafy  vegetables  are  ingested.  Certain  edible  roots  have  been 
shown  to  contain  moderate  amounts  of  this  factor,  but  the 
amounts  of  such  succulent  foods  as  would  ordinarily  be  eaten 
by  man  would  scarcely  suffice  to  meet  the  requirements  of  the 
body.  The  encouragement  of  the  dairy  industry  in  these  coun- 
tries, or  the  importation  of  liberal  amounts  of  dried  or  canned 
milk,  and  their  wider  use  in  the  diet,  together  with  the  utilization 
as  adjuvants  to  the  diet  of  fish  livers  and  other  glandular  organs 
of  animals,  and  of  eggs,  would  go  far  toward  the  elimination 
of  this  disease,  which,  provisionally,  may  be  regarded  as  a  spe- 
cific syndrome  of  dietary  origin. 

From  early  times  records  have  come  down  to  us  showing  that 
epidemics  of  dropsy  have  occurred  during  famines  caused  by 
drought  or  war.  In  the  descriptions  of  this  disorder,  it  has  been 
noted  that  hemeralopia  frequently  preceded  the  development  of 
the  edema.  It  is  said  that  night-blindness  is  endemic  in  Russia 
during  the  Lenten  Fasts.  Corneal  ulcers  and  xerosis  of  the 
conjunctiva  have  sometimes  been  noted,  among  those  who  suf- 
fered from  edema  due  to  faulty  nutrition,  and  ophthalmologists 
have  repeatedly  referred  these  eye  changes  to  poor  nourishment. 
These  eye  troubles  in  man  result  from  conditions  so  complicated 
that  it  is  not  possible  without  further  evidence,  to  attribute  all 
of  them  to  specific  starvation  for  fat-soluble  A.  There  is,  never- 
theless, a  strong  presumption  that  xerophthalmia  or  keratomal- 
acia  and  night-blindness  (hemeralopia,  nyctalopia)  not  infre- 
quently occur  as  manifestations  of  a  deficiency  of  this  dietary 
factor. 

This  conclusion  is  supported  by  the  frequent  occurrence  in 
the  literature  of  ophthalmology  of  expressions  of  the  belief  that 
malnutrition  may  bring  about  the  condition  of  defective  vision 
known  as  hemeralopia.  Illustrations  are  found  in  the  associa- 
tion of  eye  diseases  with  pellagra  by  Rampoldi  (24),  in  the 
view  of  Saweljew,  published  in  1892,  that  night-blindness  results 
from  fat  hunger  (24) ;  in  the  report  of  Roussanow  (24)  as  early 
as  1885,  that  cod  liver  oil  is  an  unfailing  remedy  for  hemeralopia, 
and  in  the  description  of  "springtime  catarrh"  and  its  associated 
conjunctivitis  by  Vetsch  (24).  These  observations  suggest  that 
a  diet  derived  too  largely  from  cereal  products,  tubers  and  other 
foods  having  similar  deficiencies,  induce  lowering  of  vitality, 
which  becomes  manifested,  among  other  ways,  in  faulty  vision. 


256       THE  NEWER  KNOWLEDGE  OF  NUTRITION 


BIBLIOGRAPHY 

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Biochem.  Zeit.,  1909,  xxii,  452. 

2.  Fingerling,  G.:     Die  Bildung  von  organischen  Phosphorverbindungen 

aus  anorganischen  Phosphaten,  Biochem.  Zeit.,  1912,  xxxviii,  448. 

3.  McCollum,  E.  V.,  Drescher,  A.  H.,  and  Halpin,  J.  G.:     Synthesis  of 

lecithin  in  the  hen  and  the  character  of  the  lecithins  produced, 
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Zeit.  f.  Biol.,  1916,  Ixvi,  350. 

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during  growth,  Jour.  Biol.  Chem.,  1915,  xxiii,  231. 

6.  Stepp:     Zur  Frage   der  synthetischen   Fahigkeiten  des  Thierkorpers, 

Zeit.  f.  Biol.,  1915,  Ixvi. 

1st  die  durch  Lipoidhunger  bedingte  Ernahrungskrankheit  identisch 

mit  beri-beri?,  Ibid.,  340. 

Die  Lipoide  unentbehrliche  Bestandteile  der  Nahrung,  Ibid.,  365. 

Beobachtungen    iiber    den    Cholesteringehalt    des    Blutes    und    der 

Galle  bei  lipoidfrei  ernahrten  Tieren,  Zeit.  f.  Biol.,  1918,  Ixix,  514. 

7.  Drummond,  J.  C.:     Researches  on  the  fat-soluble  accessory  substance. 

Observations  on  its  role  in  nutrition  and  influence  on  fat  metabolism, 
Biochem.  Jour.,  1919,  xiii,  95. 

8.  McCollum,  E.  V.,  and  Simmonds,  N.:    The  value  of  some  seed  proteins 

for  maintenance,  Jour.  Biol.  Chem.,  1917,  xxxii,  347. 
Nelson,  V.  E.,  and  Lamb,  A.  R.:    The  effect  of  vitamine  deficiency  on 
various  species  of  animals,  Amer.  Jour.  Physiol.,  1920,  li,  530. 

9.  McCollum,  E.  V.,  and  Kennedy,  C.:     The  dietary  factors  operating 

in  the  production  of  polyneuritis,  Jour.  Biol.  Chem.,  1916,  xxiv,  491. 

10.  Rohmann,  F.:     Kiinstliche  Ernahrung  und  Vitamine,  Berlin,  1916. 

11.  MacArthur,  C.  G.,  and  Luckett,  C.  L.:     Lipins  in  nutrition,  Jour.  Biol. 

Chem.,  1915,  xx,  161. 

12.  Stepp :  Experimented  Untersuchungen  iiber  die  Bedeutung  der  Lipoide 

fur  die  Ernahrung,  Zeit.  f.  Biol.,  1911,  Ivii,  135. 

13.  Knapp,  P.:     Experimenteller  Beitrag  zur  Ernahrung  von  Ratten  mit 

kiinstlicher  Nahrung  und  zum  Zusammenhang  von  Ernahrungs- 
storungen  mit  Erkranken  der  Conjunctiva,  Zeit.  f.  exper.  Pathol. 
u.  Therap.,  1909,  v,  147. 

Falta,  W.,  und  Noeggerath,  C.  T.:   Fiitterungsversuche  mit  kiinnstlicher 
Nahrung,  Hoffmeister's  Beitrage,  1906,  vii,  313. 

14.  Freise,  E.,  Goldschmidt,  M.,  und  Frank,  A.:    Der  Alkoholextract  aus 

Vegetabilien   als    Trager    Barlowheilender   Stoffe,    Monatsschrift    f. 
Kinderheilkunde,  Orig.  1913,  xii,  687.    Also  Ibid.,  1915,  xiii,  424. 
Goldschmidt,  M.:     Experimenteller  Beitrag  zur  Etiologie  der  Kerato- 
malazie,  Arch.  f.  Ophthal.,  1915,  xc,  354. 

15.  Osborne,  T.  B.,  and  Mendel,  L.  B.:     The  influence  of  butter  fat  on 

growth,  Jour.  Biol.  Chem.,  1913-14,  xvi,  423. 

16.  McCollum,  and  Simmonds:     The  minimum  requirements  of  the  two 

unidentified  dietary  factors  for  maintenance  as  contrasted  with 
growth,  Jour.  Biol.  Chem.,  1917,  xxxii,  181. 


FIG.  11. — Illustrates  a  baby  observed  and  treated  by  Dr.  C.  E.  Bloch  of  Copenhagen. 
The  child  was  suffering  from  severe  xerophthalmia  due  to  being  confined  too  largely  to 
a  diet  of  separator  skim  milk  supplemented  with  cereals.  The  right  eye  is  filled  with 
leucocytes  and  presents  a  yellow  appearance.  The  left  eye  is  swollen  shut.  The  right 
eye  was  affected  with  a  corneal  ulcer.  The  sight  of  the  right  eye  was  lost. 


XEROPHTHALMIA  (KERATOMALACIA)  257 

17.  Mori,    M.:      Ueber    der    sogenannten    Hikan    (Xerosis    conjunctivae 

infantum  ev.  Keratomalacie).    Jahrbuch  f.  Kinderheilk.,   1904,  lix, 
175. 

18.  Bloch,  C.  E.:     Eye  diseases  and  other  disturbances  in  infants  from 

deficiency  in  fat  in  the  food,  Ugeskrift  f.  Laeger,  1917,  Ixxix,  349. 
Cited  from  the  Jour.  Amer.  Med.  Assn.,  1917,  Ixviii,  1516. 
Bloch:      Clinical    investigations   of   xerophthalmia   and    dystrophy   in 
infants  and  young  children,  Jour,  of  Hyg.,  1921,  xix,  283. 

19.  Hess,  A.  F.,  and  linger,  L.  J. :    The  clinical  role  of  fat-soluble  vitamine : 

Its  relation  to  rickets,  Jour.  Amer.  Med.  Assn.,   1920,  Ixxiv,  217, 
Jan.  24. 

20.  McCollum,   and   Davis:      Reported   by    McCollum,    Harvey   Lecture 

Series   1916-17,   151.     Also    McCollum:     Jour.   Amer.   Med.   Assn., 
1917,  Ixviii,  1379. 

21.  Hopkins,  F.  G.:    The  present  position  of  vitamines  in  clinical  medicine, 

Brit.  Med.  Jour.,  1920,  147,  July  31. 

22.  Osborne,  and  Mendel:     The  incidence  of  phosphatic  urinary  calculi  in 

rats  fed   on  experimental  rations,  Jour.  Amer.   Med.   Assn.,   1917, 
Ixix,  32. 

23.  Mendel:     The  fat-soluble  vitamine,  New  York  State  Jour,  of  Med., 

1920,  xx,  212. 

24.  Krienes,    H.:      Ueber    Hemeralopie.      Speziell    Akute    idiopathische 

Hemeralopie,  Wiesbaden,  1896. 

Bayer:     Ueber  Mondblindheit,  Wiener  med.  Blatter,  1882,  iv,  No.  21. 
Braunschweig:    Zur  Kenntniss  d.  Xerosis  conjunctivae,  Fortschritte  d. 

Med.,  1890,  No.  23. 
Dumas :  Contribution  a  1 'etude  de  Phemeralopie  essentielle,  etc.    These 

de,  Paris,  1889. 

Husemann:     Zur  Tabaksamaurose,  Deutsch.  med.  Woch.,  1894,  819. 
Rampoldi:     Pellagra  u.  Augenkrankheiten,  Annal.  d'Ottal,  1885,  fasc. 

2,  3.    Zentralbl.  f.  Augenheilk.,  1885,  498. 
Roussanow:     Der  Fischleberthran,  ein  fast  unfehlbares  Mittel  gegen 

die  Hemeralopie,  Wratsch,  No.  16,  1885.    Cited  by  Krienes. 
Ssaweljew:     Die  Nachtblindheit  als  Folge  von  Fetthunger,  Wjestnik. 

studeb.  medic.,  1892.    Cited  by  Krienes. 
Schtschepotiew :     Beitrage  zur.  Lehre  von  Huhnerblindheit,  Wratsch, 

1892,  No.  42.    Cited  by  Krienes. 
Vetsch:     Ueber  den   Friihjahrskatarrh  der  conjunctiva,  Inaug.  Diss., 

1878.    Cited  by  Krienes. 

25.  De  Gouvea:    Beitrage  zur  Kenntniss  der  Hemeralopie  u.  Xerophtomie 

aus  Ernahrungsstorungen,  v.  Graefes  Arch.  f.  Ophthal,  Bd.  xxix,  167. 

26.  Little,  A.  D.:     Beri-beri  caused  by  fine  white  flour,  Jour.  Amer.  Med. 

Assn.,  1912,  Iviii,  2029. 

Walcott,  A.  M.:  Beri-beri  in  the  Amazon  basin,  Jour.  Amer.  Med. 
Assn.,  1915,  Ixv,  2145. 

Hrdlicka,  A.:  Medical  and  physiological  observations  on  the  Indians 
of  the  Southwest,  Bull.  34.  Bureau  of  American  Ethnology,  Wash- 
ington. 

Czenry,  C.,  and  Keller,  A.:  Die  Ernahrung  des  Kindes,  Leipsic,  1906, 
pt.  2.  67. 

Lovelace,  C.:  The  etiology  of  beri-beri,  Jour.  Amer.  Med.  Assn.,  1912, 
lix,  2134. 

27.  Young,  Ann:    Personal  communication. 


CHAPTER  XII 

CHEMICAL  STUDIES  OF  THE  DIETARY  ESSENTIAL, 
FAT-SOLUBLE  A 

286.  Best  Sources  of  Fat-Soluble  A. — There  has  been  much 
interest  shown  among  a  group  of  chemists  in  the  problem  of 
determining  the  nature  of  the  dietary  essential,  fat-soluble  A, 
but  little  has  been  achieved  in  this  direction.     The  history  of 
the  studies  relating  to  this  phase  of  nutrition  is  sufficiently  inter- 
esting  and   instructive  to  warrant   its   inclusion   as   a   special 
chapter.    Biological  tests  have  revealed  the  distribution  of  this 
dietary  factor  among  our  more  important  foods,  and  the  relative 
abundance  with  which  it  occurs  in  a  long  list  of  articles  of  animal 
and  vegetable  origin  is  well  known.    Among  the  fats,  the  best 
sources  are  cod  liver  oil,  butter  fat  and  egg  yolk  fats.     Some 
leaves  of  plants  are  known  to  be  excellent  sources,  and  there  is 
good  reason  to  believe  that  most  of  the  unspecialized  leaves 
(those  not  modified  as  storage  tissues)    contain  it  in  relative 
abundance.    In  various  parts  of  the  world,  grazing  and  browsing 
animals  live  exclusively  or  nearly  so  on  the  leaves  of  grasses  or 
of  trees,  thus  deriving  their  sole  supply  of  fat-soluble  A  from 
this  source. 

287.  Distribution  of  Fat-Soluble  A  in  Vegetable  Foods. — 
The  early  experiments  of  McCollum  and  his  co-workers  yielded 
results  which  seemed  to  warrant  the  generalization  that,  when 
estimated  on  the  basis  of  the  nutritive  needs  of  the  rat,  all  seeds, 
of  plants,  tubers  and  fleshy  roots  were  decidedly  deficient  in 
this  substance.    This  judgment  rested  on  their  observation  that 
all  foods  they  examined,  which  were  functionally  storage  tissues 
of  plants,  could  be  enhanced  in  their  dietary  properties  by  the 
addition  of  butter  fat.    This  generalization  still  appears  to  be 
justified,  although  with  certain  reservations  which  at  that  time 
could  not  be  discerned.    There  is  room  for  difference  of  opinion 
among   students   of  nutrition   concerning   what   constitutes   an 
adequate  amount  of  any  dietary  essential.     One  worker  may 
make  the  basis  of  his  judgment  the  ability  of  an  animal  to 

258 


CHEMICAL  STUDIES  OF  FAT-SOLUBLE  A        259 

grow  in  an  apparently  normal  manner  to  approximately  the 
full  adult  size  and  may  thus  be  led  to  the  belief  that  a  certain 
intake  of  fat-soluble  A  is  adequate.  Another  worker,  planning 
his  experiments  so  as  to  cover  the  entire  life  history  of  his  ani- 
mals, may  find  that  the  minimum  amount  of  the  factor  in 
question  which  will  just  serve  for  the  support  of  normal  growth 
and  the  apparent  maintenance  of  health  during  several  months, 
is  inadequate  when  the  entire  span  of  life  is  taken  into  account, 
and  that  a  degree  of  deficiency  which  did  not  make  itself  appar- 
ent in  the  shorter  period  of  observation  is  easily  detected  in  the 
appearance  of  early  deterioration  and  aging.  The  fertility  may 
be  affected  as  may  infant  mortality,  or  there  may  ensue  defective 
development  of  the  bones  or  teeth  or  both.  Much  depends  upon 
the  standards  of  the  investigator  concerning  what  constitutes 
"normal"  nutrition.  As  will  be  pointed  out  in  a  later  chapter, 
we  have  come  to  hold  the  view  that  "normal"  is  not  a  good 
word  to  use  in  nutrition  studies.  Optimal  well-being,  the  best 
condition  which  can  be  reached,  should  serve  as  the  standard 
of  comparison. 

288.  Yellow  Maize  Contains  More  Fat-Soluble  A  Than 
White  Varieties. — An  extremely  interesting  observation  was 
made  by  Steenbock  and  Gross  (1)  in  1919.  They  discovered 
that  carrots  and  yellow  sweet  potatoes  are  relatively  rich  in  the 
substance  fat-soluble  A,  whereas  red  beets,  parsnips,  rutabagas, 
sugar  beets,  potatoes,  mangels  and  dasheens  are  very  poor  in  it. 
Steenbock  and  Boutwell  (2)  found  yellow  maize  a  sufficiently 
good  source  of  the  fat-soluble  A  to  support  approximately  the 
average  amount  of  growth  in  a  male  and  a  female  rat  when  this 
cereal  formed  83  per  cent  of  the  diet,  and  when  it  was  satis- 
factorily supplemented  with  respect  to  inorganic  deficiencies. 
The  male  appeared  rough-coated  after  the  age  of  eight  months. 
The  female  produced  ten  litters  of  young.  The  first  eight  of 
these  all  died  a  few  days  after  birth,  but  the  last  two  litters  were 
reduced  to  three  and  four  young,  respectively,  and  were  satis- 
factorily nursed  to  a  state  of  independence  by  the  mother.  White 
maize,  on  the  other  hand,  was  found  without  exception  to  be 
very  deficient  in  this  dietary  factor,  although  several  varieties 
were  tested.  Animals  which  derived  a  large  part  (85  per  cent) 
of  their  food  from  white  maize  failed  to  grow  beyond  a  very 
limited  degree  and  suffered  from  xerophthalmia  and  debility  of 
the  skin  as  shown  by  incrustation  of  the  ears,  warts  on  the  nose, 
infections  of  the  tail  and  feet,  and  sores  on  the  body.  These 


260      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

skin  conditions  are  apparently  due  to  lack  of  resistance  of  the 
skin  to  invasion  by  an  itch  mite,  although  Steenbock  and  Bout- 
well  make  no  mention  of  this.  McCollum  and  Simmonds,  in 
their  earlier  experience  frequently  observed  these  conditions  in 
poorly  nourished  rats,  and  microscopic  examination  of  material 
from  the  lesions  revealed  the  presence  of  large  numbers  of  very 
small  mites.  In  recent  years,  they  have  been  able  to  eradicate 
this  parasite  from  their  colony,  and  the  lesions  described  by 
Steenbock  and  Boutwell  have  entirely  disappeared.  Such  skin 
conditions  are  not,  therefore,  to  be  regarded  as  in  any  way  asso- 
ciated with  this  type  of  specific  starvation. 

Red  maize,  which  was  free  from  yellow  pigment  was  likewise 
found  to  be  free  from  fat-soluble  A,  whereas  red  maize  which 
contained  yellow  pigment  proved  a  fairly  good  source  of  this 
substance.  Variegated  maize,  in  which  the  pigments  were  irregu- 
larly distributed  and  which  on  that  account  contained  red,  yel- 
low and  blue  pigmented  portions,  as  well  as  some  white  areas, 
gave  results  in  feeding  experiments  which  were  intermediate 
between  white  on  the  one  hand  and  deeply  yellow  pigmented 
varieties  on  the  other.  Where  yellow  kernels  occurred  mixed 
with  white  in  variegated  ears,  a  selection  of  the  two  kinds  showed 
by  appropriate  tests  that  the  former  contained  distinctly  more 
fat-soluble  A  than  the  latter. 

289.  Certain  Leaves  Are  Very  Rich  in  Fat-Soluble  A. — It 
was  pointed  out  in  1917  by  McCollum,  Simmonds  and  Pitz  (3) 
that  the  alfalfa  leaf  is  several  times  richer  in  fat-soluble  A  than 
are  such  grains  as  wheat,  maize  or  oat  kernel.  This  line  of  in- 
vestigation has  been  furthered  by  Osborne  and  Mendel  (4) ,  who 
have  found  spinach,  alfalfa  leaves  and  clover  leaves,  to  be  rela- 
tively rich  in  both  fat-soluble  A  and  water-soluble  B.  Ten  per 
cent  of  one  of  these  leaves  in  a  diet  which  derived  its  sole 
content  of  fat-soluble  A  therefrom,  proved  an  adequate  source 
of  this  dietary  essential  for  the  promotion  of  fairly  rapid  growth 
during  periods  up  to  170  days.  Timothy  proved  somewhat  less 
valuable  for  this  purpose.  These  results  show  clearly  that  these 
leaves  are  excellent  sources  of  this  vitamin.  Cabbage,  a  thick 
leaf,  specialized  as  a  storage  organ,  was  distinctly  poorer  in 
both  the  uncharacterized  essentials  under  consideration  than 
were  thin  leaves. 

Steenbock  and  Gross  (5)  extended  these  studies  and  found 
that  5  per  cent  of  immature  alfalfa  leaf  in  the  diet  as  the  sole 
source  of  the  fat-soluble  A,  the  remainder  of  the  diet  being 


CHEMICAL  STUDIES  OF  FAT-SOLUBLE  A        261 

satisfactorily  constituted,  sufficed  to  support  normal  growth,  and 
allowed  the  rearing  of  some  young.  Lettuce,  spinach  and  chard 
contain  fat-soluble  A  in  similar  amounts,  but  lettuce  appeared 
to  be  somewhat  poorer  than  the  other  leaves  studied.  Cabbage 
was  found  to  be  deficient,  in  comparison  with  other  leaves,  in 
its  content  of  fat-soluble  A.  These  investigators  repeatedly  em- 
phasized their  conviction  that  the  substance  fat-soluble  A  is 
intimately  associated  with  yellow  pigmentation.  Those  leaves 
which  contained  much  yellow  pigment,  although  masked  by  the 
green  pigment  chlorophyll,  were  richer  than  cabbage,  which  con- 
tains little  yellow  pigment. 

290.  Drummond  Suggests  That  Fat-Soluble  A  Is  One  of 
the  Plant  Yellow  Pigments. — Among  the  vegetable  foods,  there- 
fore, the  distribution  of  fat-soluble  A  appears  to  be  associated 
in  a  remarkable  way  with  yellow  pigmentation.    The  parallelism 
seemed  to  Drummond  (6)  sufficient  to  warrant  an  investigation 
to  determine  whether  this  substance  might  be  one  of  the  yellow 
pigments  of  plants.    He  brought  rats  into  a  condition  in  which 
they  were  suffering  from  fat-soluble  A  deficiency,  and  then  fed 
them  pure   and   impure  preparations   of  the  pigment   carotin, 
which,  together  with  xanthophyll,  constitutes  the  pigments  to 
which  are  due  the  yellow  color  of  many  vegetable  products.    The 
animals  did  not  respond  with  growth  and  did  not  remain  free 
from  ophthalmia,  as  they  would  have  done  had  a  fat  containing 
fat-soluble  A  been  administered.    The  results  indicated,  there- 
fore, that  carotin  is  not  identical  with  fat-soluble  A. 

About  the  same  time  Steenbock  (7)  expressed  the  belief 
that  the  fat-soluble  A  is  one  of  the  yellow  plant  pigments, 
although  he  and  Boutwell  (8)  had  earlier  stated  that  this  vita- 
min is  not  carotin.  In  several  later  papers  Steenbock  has  pre- 
sented data  showing  the  remarkable  association  of  this  sub- 
stance with  the  yellow  pigment  of  plants.  He  has  shown  that 
when  carotin  and  xanthophyll  are  separated,  fat-soluble  A  ac- 
companies carotin,  whereas  the  xanthophyll  fraction  is  poor  in  it. 

Drummond  and  his  co-workers  have  energetically  pushed  their 
investigations  in  the  testing  of  the  hypothesis  that  there  is  a 
relation  between  yellow  pigmentation  and  content  of  fat-soluble 
A  in  food-stuffs.  They  tested  twenty-four  different  fats  and 
oils  which  were  pigmented  to  widely  differing  degrees  for  their 
efficiency  as  sources  of  this  dietary  essential,  and  could  discover 
no  relation  between  vitamin  content  and  color  (9). 

291.  Stevenson's  Observation  on  Carotin. — An  exceedingly 


262      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

interesting  observation  has  been  recorded  by  Stevenson  (10) 
working  in  the  laboratory  of  F.  G.  Hopkins.  She  states  that 
an  impure  preparation  of  carotin,  which  did  not  behave  like  a 
source  of  fat-soluble  A  when  fed  as  such,  acquired  the  properties 
of  this  dietary  factor  when  it  was  dissolved  in  palm-kernel  oil 
previously  tested  and  found  ineffective  for  the  stimulation  of 
growth.  This  observation  deserves  the  most  careful  attention, 
for  if  substantiated,  it  would  seem  to  indicate  that  fat-soluble 
A  may  not  be  absorbable  and  utilizable  unless  it  is  carried  by 
at  least  small  amounts  of  fats.  She  reports  also  that  butter  fat 
can  be  decolorized  of  its  yellow  pigment  by  absorbing  the  carotin 
with  charcoal  and  without  impairing  in  any  way  its  value  as  a 
source  of  fat-soluble  A.  It  will  be  seen,  therefore,  that  the  evi- 
dence up  to  this  time  is  decidedly  conflicting  on  the  point  as  to 
the  relation  between  yellow  pigment  and  content  of  fat-soluble  A. 

Palmer  and  Kennedy  (11)  have,  however,  published  an 
excellent  paper  on  this  subject  which  finally  disposes  of  the 
question,  for  they  prove  conclusively  that  there  is  no  correlation 
between  the  pigmentation  of  certain  foods  and  their  value  as 
a  source  of  fat-soluble  A.  A  brief  history  of  Palmer's  studies 
should  precede  the  discussion.  Palmer  first  took  issue  with 
Steenbock  on  the  basis  of  the  former's  observation  that  cotton- 
seed oil,  when  freed  from  its  resinous  substance,  possesses  a  fine 
golden  yellow  color  and  is  rich  in  carotinoids,  but  does  not  con- 
tain demonstrable  amounts  of  fat-soluble  A  (12).  He  also 
showed  that  the  blood  of  certain  species  of  animals,  as  sheep, 
swine,  dog,  cat,  rabbit,  and  guinea  pig,  is  free  from  carotinoids. 
This  would  seem,  if  the  vitamin  were  one  of  the  pigments,  to 
preclude  the  entrance  of  the  substance  into  the  tissues  of  these 
animals.  Dolly  and  Guthrie  (13)  found  adipose  tissues  and 
nerve  cells  of  these  animals  to  be  free  from  carotinoid  pigments. 

292.  Chickens  Can  Be  Reared  on  Diets  Containing  No 
Yellow  Pigments. — Palmer  and  Kempster  (14)  succeeded  in 
growing  chicks  from  hatching  on  a  mixture  of  white  maize, 
white  maize  meal,  white  maize  bran,  skim  milk  and  bone  meal. 
After  six  weeks  the  birds  began  to  fail,  but  responded  at  once 
when  pork  liver  was  added  to  their  diet.  The  latter  they  showed 
to  be  free  from  carotinoids.  At  three  months  of  age  the  birds 
were  normal  in  size  for  their  age.  They  were  then  given  an 
occasional  feeding  of  white  summer  squash  and  white  Spanish 
onions.  There  was  but  a  trace  of  carotinoids  in  the  tissues  of 
the  birds  when  grown,  as  was  shown  by  the  lack  of  pigmenta- 


CHEMICAL  STUDIES  OF  FAT-SOLUBLE  A       263 

tion  of  the  shanks,  ear  lobes,  beaks  and  other  parts  of  the  body. 

At  the  age  of  six  months  the  hens  began  to  lay,  and  seventeen 
of  them  produced  893  eggs  in  233  days.  One  hen  laid  88  eggs 
during  this  period.  The  yolks  were  found  to  be  free  from 
carotinoids.  A  large  number  of  these  eggs  were  incubated. 
Viable  chicks  were  hatched,  which  were  normal  in  every  respect 
except  for  the  absence  of  yellow  pigment  from  the  shanks,  beaks 
and  other  parts.  From  these  results  it  appears  that  further 
attempts  to  establish  a  relationship  between  a  yellow  pigment 
and  fat-soluble  A  are  futile. 

293.  Palmer  and  Kennedy's  Disproof  of  the  Yellow  Pig- 
ment Theory. — The  investigation  of  Palmer  and  Kennedy,  re- 
ferred to  above,  appears  to  add  the  last  word  to  this  discussion, 
and  to  leave  no  further  room  for  doubt  that  the  presence  of 
liberal  amounts  of  fat-soluble  A  in  certain  yellow  pigmented 
vegetable  tissues,  and  its  absence  from  other  varieties  of  the 
same  species  not  possessing  yellow  color,  is  fortuitous.  These 
investigators  succeeded  in  demonstrating  that  approximately 
normal  growth  and  reproduction  can  be  secured  in  the  albino 
rat  on  rations  free  from  carotinoid  pigments  but  rich  in  fat- 
soluble  A. 

They  first  made  a  critical  study  of  the  presence  of  carotinoid 
pigments  in  the  albino  rat  and  then  instituted  growth  experi- 
ments with  this  species,  using  colorless  ewe's  milk  fat  as  the  sole 
source  of  fat-soluble  A.  In  other  experiments  they  used,  instead 
of  ewe  milk  fat,  colorless  egg  yolk  as  a  source  of  this  factor.  The 
liver,  blood,  spleen,  suprarenals,  adipose  tissue,  ovary  and  the 
fat  of  milk  recovered  from  the  stomachs  of  very  young  rats  were 
examined  with  every  precaution  for  thoroughness  to  determine 
the  presence  of  carotinoid  pigments.  The  rat  milk  was  abso- 
lutely colorless,  as  was  also  the  fat  separated  from  the  adipose 
tissue.  The  fat  of  the  blood,  suprarenals,  spleen  and  ovaries, 
and  also  the  liver  tissue  of  new-born  rats  was  entirely  devoid 
of  color.  The  liver  of  adult  rats  fed  a  diet  containing  an  abun- 
dance of  plant  carotinoids,  yielded  an  oil  which  was  yellowish, 
but  the  pigment  did  not  give  any  of  the  tests  characteristic  of 
carotin.  This  substance  cannot,  therefore,  be  regarded  as  in  any 
way  related  to  those  plant  pigments  with  which  fat-soluble  A 
may  be  concerned. 

The  milk  of  the  ewe  is  almost  colorless,  but  gives  a  very  faint 
test  for  plant  carotinoids.  Nine  per  cent  of  the  diet  consisted  of 
this  fat,  and  it  was  estimated  that  the  ration  contained  thereof 


264     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

but  0.127  parts  in  a  million.  The  diet  employed  consisted  of 
purified  casein,  a  suitable  salt  mixture,  agar,  ewe  milk  fat,  and 
dextrin  carrying  the  alcoholic  extract  of  ether  extracted  wheat 
embryo  or  germ  to  serve  as  a  source  of  water-soluble  B.  The 
latter  proved  an  inadequate  source  of  the  factor  B  and  was 
afterwards  supplemented  by  2  per  cent  of  baker's  yeast. 

On  this  diet  the  rats  grew  fairly  well  during  two  and  a  half 
to  three  months,  and  three  females  each  produced  litters  of 
eleven  young.  Two  of  these  mothers  were  able  to  nurse  their 
litters,  which  were  reduced  to  six  in  each  case.  The  young  grew 
in  an  essentially  normal  manner.  On  a  similar  diet  in  which  15 
per  cent  of  colorless  egg  yolks  served  as  the  sole  source  of  fat- 
soluble  A,  six  rats  grew  well,  two  increasing  in  weight  from 
about  70  grams  to  about  230  grams.  Two  females  produced  each 
a  litter  of  young  which  were  normally  nourished. 

Palmer  and  Kennedy  also  pointed  out  certain  numerical  rela- 
tions between  the  carotin  content  and  fat-soluble  A  efficiency  of 
various  foods.  These  varied  within  very  wide  limits.  Thus,  15 
per  cent  of  their  egg  yolks  containing  no  carotin,  were  at  least 
equivalent  as  sources  of  fat-soluble  A  to  85  per  cent  of  yellow 
maize,  although  the  latter  amount  furnished  1,400  parts  per 
million  of  carotin.  Five  per  cent  of  ewe  milk  fat,  they  estimated 
to  be  equivalent  as  a  source  of  fat-soluble  A  to  1  per  cent  of 
dry  spinach.  The  carotin  content  of  one  million  parts  of  rations 
containing  these  amounts  of  materials  would  amount  to  0.073 
and  160  parts  per  million,  respectively.  The  second  of  these 
two  diets  containing  about  the  same  amounts  of  fat-soluble  A 
would  contain  about  twenty-two  hundred  times  as  much  pig- 
ment as  the  former. 

294.  The  Stability  of  Fat-Soluble  A  Toward  Heat.— In  re- 
gard to  the  stability  of  the  fat-soluble  A  toward  heat  and  re- 
agents, there  has  existed  much  difference  of  opinion.  McCollum 
and  Davis  (15)  observed  that  egg  yolks  which  had  been  hard 
boiled  were  still  a  good  source  of  this  vitamin,  and  also  that 
the  melting  of  butter  in  a  hot  water  funnel  and  its  nitration  dur- 
ing one  or  two  hours,  followed  by  solution  in  ether,  filtration 
and  subsequent  evaporation  of  the  ether  did  not  appreciably 
lower  the  content  of  fat-soluble  A.  They,  therefore,  reported 
that  the  substance  is  fairly  stable  at  high  temperatures.  In 
testing  their  butter  fats  and  egg  yolk  fats,  they  employed  in 
their  feeding  experiments  3  to  5  per  cent  of  one  or  the  other  as 
the  sole  source  of  fat-soluble  A,  and  judged  from  their  findings 
that  no  extensive  destruction  could  have  taken  place. 


CHEMICAL  STUDIES  OF  FAT-SOLUBLE  A       265 

Osborne  and  Mendel  (16)  passed  live  steam  through  butter 
fat  for  two  and  a  half  hours,  and  found  that  18  per  cent  of  this 
fat  in  a  diet  served  to  support  normal  growth,  when  there  was 
no  other  source  of  fat-soluble  A.  Since  they  used  such  very  high 
fat  intake  they  could  have  destroyed  at  least  four-fifths  of 
the  substance  and  still  had  enough  left  to  insure  a  successful 
growth  experiment.  Mendel  has  recently  stated  that  butter  fat 
heated  for  many  hours  to  96°  C.  would  still  suffice  as  a  source  of 
fat-soluble  A  when  0.25  gram  per  day  was  included  in  the  diet 
of  the  rat.  This  may  be  roughly  estimated  to  form  about  2.5 
per  cent  of  the  food  mixture.  Their  data,  therefore,  support  the 
view  that  fat-soluble  A  is  a  relatively  stable  substance  at  high 
temperatures. 

Steenbock,  Boutwell  and  Kent  (17)  took  issue  with  the  state- 
ments recorded  in  the  preceding  paragraph.  They  stated: 
"When  butter  fat  is  heated  for  4  hours  at  100°,  so  much  of  its 
vitamine  may  be  destroyed  that  with  our  basal  rations,  using  rats 
as  the  experimental  animal,  no  demonstrable  amounts  of  the 
vitamine  remained."  Steenbock  and  Boutwell  (18)  have,  how- 
ever, recently  reported  that  plant  tissues  such  as  yellow  maize, 
chard,  carrots,  sweet  potatoes,  and  squash,  may  be  autoclaved 
at  fifteen  pounds  pressure,  without  causing  any  noticeable  de- 
struction of  fat-soluble  A. 

295.  Fat-Soluble  A  Is  Easily  Destroyed  by  Oxidation. — 
Hopkins  (19)  and  also  Drummond  (20)  have  shown  that  oxida- 
tion readily  destroys  the  activity  of  fat-soluble  A.     It  may, 
therefore,  be  accepted  that  the  substance  is  stable  toward  high 
temperatures  in  the  absence  of  oxygen. 

296.  Extraction  of  Fat-Soluble  A  from  Foods  by  Means 
of  Solvents. — McCollum,  Simmonds  and  Pitz  (21)  were  the  first 
to  study  the  possibility  of  extracting  the  dietary  essential  fat- 
soluble  A  from  plant  tissues.     It  was  stated,  as  the  result  of 
experiments  with  several  plant  oils,  that  this  substance  "is  not 
extracted  from  plants  with  the  fats  by  such  solvents  as  ether, 
chloroform,  benzene  or  acetone,  and  is  therefore  not  found  in 
any  fats  or  oils  of  plant  origin.    Hot  alcohol  does  remove  it 
from  plant  tissues.*'    The  solubility  of  the  substance  in  alcohol 
was  based  upon  data  obtained  with  the  maize  kernel.    Steenbock 
and  Boutwell  (22)  later  stated  "while  the  vitamine  (fat-soluble 
A)   is  not  extracted  from  maize  by  ether,  alcohol  removes  it 
quantitatively  and  with  little,  if  any,  destruction."    Steenbock 
and  Boutwell  misrepresented  the  views  of  McCollum,  Simmonds 
and  Pitz,  for  after  quoting  the  above  statement  from  their  paper 


266     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

they  add:  "the  reference  to  its  solubility  in  alcohol  (in  the  paper 
of  McCollum,  Simmonds  and  Pitz)  is  based  on  data  obtained 
with  the  maize  kernel  which  in  themselves  are  not  acceptable  as 
McCollum,  Simmonds  and  Pitz  were  of  the  opinion  that  maize 
generally  was  very  deficient  in  the  fat-soluble  vitamine."  They 
referred  to  an  article  in  the  Journal  of  Biological  Chemistry,  vol. 
28,  1916-17,  p.  154,  in  which  McCollum,  Simmonds  and  Pitz 
stated  that  "the  maize  kernel  contains  both  the  unidentified 
dietary  factors,  fat-soluble  A  and  water-soluble  B.  The  former 
is  present  in  amount  too  small  for  the  maintenance  of  growth  at 
the  maximum  rate  in  rats,  and  regardless  of  how  satisfactorily 
the  maize  kernel  is  supplemented  in  other  respects,  failure  of  per- 
fect nutrition  will  supervene  within  a  few  months  unless  some 
food-stuff,  containing  fat-soluble  A  (butter  fat,  certain  other 
fats,  leaves  of  plants,  etc.)  is  supplied."  In  another  place  McCol- 
lum and  Davis  (23)  stated  that:  "50  per  cent  of  corn  added  to 
the  fat- free  diet  is  vastly  superior  to  5  per  cent  of  butter  fat  (as 
a  source  of  fat-soluble  A)  when  the  animals  have  been  brought 
to  a  point  near  which  failure  of  nutrition  would  set  in."  These 
quotations  make  clear  how  little  basis  Steenbock  and  Boutwell 
had  for  their  statement  that  McCollum  and  his  co-workers  had 
made  an  unwarranted  claim  concerning  their  demonstration  of 
the  solubility  of  fat-soluble  A  in  alcohol,  and  that  they  "were 
of  the  opinion  that  maize  generally  was  very  deficient  in  the 
fat-soluble  vitamine." 

It  has  been  shown  by  Osborne  and  Mendel  (24)  and  by  Steen- 
bock and  Boutwell  (22)  that  from  certain  vegetable  materials, 
especially  leafy  structures,  ether  or  benzene  may  extract  a  cer- 
tain amount  of  fat-soluble  A,  whereas  water  is  entirely  inef- 
fective. 

297.  Fat-Soluble  A  Is  Not  Destroyed  by  Saponifying 
Agents, — In  1914  McCollum  and  Davis  observed  that  butter  fat 
may  be  saponified  with  alcoholic  potassium  hydroxid  and  pe- 
troleum ether  without  the  destruction  of  the  nutritive  principle 
now  designated  fat-soluble  A  or  fat-soluble  vitamin  (25).  The 
soaps  resulting  from  this  saponification  were  dissolved  in  water 
and  shaken  with  olive  oil.  This  olive  oil  had  been  shown  by 
previous  experiments  to  be  ineffective  as  a  substitute  for  butter 
fat  for  the  promotion  of  growth  when  added  to  an  otherwise 
complete  diet.  The  olive  oil,  which  had  thus  been  in  intimate 
contact  with  the  soaps  of  butter  fat,  was  then  removed  by  ether, 
and  the  latter  evaporated.  This  olive  oil  was  found  by  appro- 


CHEMICAL  STUDIES  OF  FAT-SOLUBLE  A       267 

priate  experiments  to  have  acquired  the  nutritive  properties  of 
the  butter  fat,  since  it  caused  a  marked  response  with  growth 
in  rats  which  had  been  denied  the  dietary  essential  fat-soluble 
A,  and  whose  growth  had  been  for  that  reason  suspended.  This 
experiment  showed  that  the  dietary  essential  in  butter  fat  is 
sufficiently  stable  to  withstand  saponification  in  nonaqueous 
solutions.  Steenbock,  Sell  and  Buell  (26)  have  since  recorded  as 
an  original  observation  their  findings  that  fat-soluble  vitamin 
resists  saponification  in  the  cold  by  alcoholic  potash. 

The  foregoing  account  of  the  investigations  which  have  been 
directed  toward  discovering  methods  for  the  isolation  and  purifi- 
cation of  the  dietary  essential  fat-soluble  A,  have  actually 
yielded  only  the  information  that  the  substance  is  thermostable 
in  the  absence  of  oxygen,  that  it  will  withstand  the  action  of 
saponifying  agents  in  the  absence  of  water,  and  that  after 
saponification  it  accompanies  the  carotin  fraction  of  the  plant 
pigments  rather  than  the  xanthophyll.  We  have  no  knowledge 
concerning  the  chemical  nature  of  the  substance,  and  it  is  to  be 
hoped  that  the  near  future  will  bring  important  results  in  the 
direction  of  revealing  its  properties  and  its  chemical  composition. 

298.  Methods  of  Estimating  the  Content  of  Fat-Soluble  A 
in  Natural  Food-Stuffs. — So  much  interest  is  shown  nowadays 
in  the  relative  values  of  different  foods  as  sources  of  the  different 
vitamins,  that  students  will  welcome  a  brief  account  of  the  pro- 
cedures and  their  effectiveness  as  means  of  determining  quan- 
titatively the  factor  fat-soluble  A. 

It  would  seem  logical  to  test  the  proposition  that  young  ani- 
mals, restricted  to  diets,  otherwise  satisfactory  but  containing 
less  than  the  minimum  amount  of  fat-soluble  A  necessary  for  the 
promotion  of  growth  at  the  optimum  rate,  would  grow  at  rates 
proportional  to  the  supply  of  this  dietary  essential,  the  limiting 
factor.  If  this  were  true,  it  should  be  possible  on  a  carefully 
planned  diet  to  judge  from  the  rate  of  growth  in  a  number  of 
individuals  the  nutritive  value  of  that  diet  with  respect  to  this 
substance.  This  possibility  has  been  thoroughly  tested  by  Mc- 
Collum  and  Simmonds  but  the  results  are  disappointing.  With 
suboptimal  amounts  of  fat-soluble  A,  young  rats  fail  to  respond 
in  a  manner  which  can  be  safely  used  as  a  basis  of  accurate 
comparison  of  the  amounts  tested.  Nevertheless,  rough  approxi- 
mations of  the  comparative  values  of  different  foods  for  this 
dietary  factor  are  possible.  Osborne  and  Mendel  (4)  and  Steen- 
bock and  his  co-workers  (5)  have  reported  studies  of  this  nature 


268     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

which  show  the  great  superiority  in  their  content  of  fat-soluble 
A  of  several  leafy  vegetables  over  the  cereal  grains. 

A  test  which  has  been  much  used  by  McCollum  and  Simmonds 
(27)  is  carried  out  by  employing  as  test  animals  young  rats  of 
the  same  stock,  age  and  previous  nutritive  history.  They  are 
placed  upon  a  diet  which  is  lacking  or  essentially  lacking  in 
fat-soluble  A.  A  mixture  of  rolled  oats  40.0,  gelatin  10.0,  a  salt 
mixture  3.7,  and  dextrin  46.3  per  cent,  respectively,  serves  this 
purpose  well.  When  the  initial  weights  of  the  animals  are  about 
55  grams,  and  their  ages  about  40  days,  they  usually  develop  a 
circular  area  of  puffiness  surrounding  the  eyes  in  about  30  to  35 
days.  This  sign  is  premonitory  of  the  onset  of  ophthalmia,  which 
will  now  develop  within  a  few  days  and  which  is  accompanied 
by  excessive  secretion  in  the  eyes,  and  marked  edema  of  the  lids. 
These  external  signs  of  ophthalmia  are  all  that  need  be  consid- 
ered here.  Unless  the  eyes  are  profoundly  damaged  recovery 
takes  place  on  the  inclusion  in  the  diet  of  a  suitable  amount  of 
fat-soluble  A.  For  the  purpose  of  standardizing  conditions  with 
a  view  to  perfecting  a  quantitative  test  for  this  dietary  factor 
they  selected,  for  the  addition  of  the  source  of  fat-soluble  A,  the 
time  when  the  puffy  ring  was  easily  seen,  but  when  no  decided 
increase  in  secretion  had  as  yet  begun.  By  comparing  the 
amounts  of  different  food  substances  given  heat  or  any  other 
treatment  tending  to  destroy  the  anti-ophthalmic  factor  neces- 
sary to  interrupt  the  course  of  the  disease  or  to  prevent  the  de- 
velopment of  a  severe  form  of  ophthalmia,  they  were  able  to 
make  fairly  satisfactory  comparisons  of  different  foods  with  re- 
spect to  their  curative  properties.  This  method  has  the  advan- 
tage of  requiring  less  time  and  less  material  than  are  necessary 
in  a  growth  experiment.  Moreover,  the  method,  they  believe, 
yields  results  which  are  more  satisfactory.  In  this  method, -the 
animals  are  brought  to  the  verge  of  an  acute  eye  disorder,  which 
is  averted  by  an  exhibition  of  a  certain  quantity  of  the  sub- 
stance of  which  their  bodies  are  depleted.  The  period  of  obser- 
vation is  shortened  to  about  6  or  8  weeks. 

This  method  has,  however,  one  element  of  weakness.  A 
subjective  factor  is  involved  in  determining  the  time  for  begin- 
ning the  administration  of  curative  measures,  but  this  is  reduced 
to  a  minimum  because  of  the  fairly  definite  and  easily  observ- 
able incipient  edema,  and  the  certainty  that  once  this  is  seen, 
the  animals  will  develop  severe  ophthalmia  within  a  few  days. 

When  small  rats  are  placed  on  a  diet  containing  traces  of  the 


CHEMICAL  STUDIES  OF  FAT-SOLUBLE  A       269 

factor  fat-soluble  A,  there  is  frequently  observed  a  remarkable 
variation  in  the  time  necessary  to  bring  about  ophthalmia.  In 
our  experience  animals  weighing  35  grams  suffered  from  it  within 
3  to  4  weeks,  but  in  one  group  of  13,  individuals  were  recorded 
as  showing  it  after  21,  26,  28,  37,  39  days,  respectively,  while  one 
showed  no  signs  until  the  125th  day.  Since  we  have  no  chemical 
reaction  by  means  of  which  fat-soluble  A  can  be  detected  or 
estimated,  the  biological  test  described  appears  to  be  the  most 
satisfactory  one  available. 

299.  Pathological  Changes  Resulting  from  Lack  of  Fat- 
Soluble  A. — For  the  purpose  of  determining  the  physiological 
role  which  each  of  the  vitamins  plays,  it  is  necessary  that  we 
should  learn  as  precisely  as  possible  what  happens  to  the  cells 
composing  the  different  tissues  when  a  break  is  induced  in 
metabolism  through  specific  starvation  for  a  single  one  of  these, 
when  no  other  nutritive  principle  is  involved  in  bringing  about 
metabolic  disaster.  Research  in  this  direction,  which  must  be 
achieved  through  the  cooperation  of  the  biochemist  and  the 
histologist  with  knowledge  of  pathology,  may  be  expected  to 
prove  highly  fruitful.  As  yet,  however,  little  effort  has  been 
directed  to  this  undertaking.  Many  attractive  chemical  prob- 
lems of  a  specific  nature  have  held  the  attention  of  the  chemists 
in  this  new  field.  These  could  be  studied  through  observing  the 
effects  on  growth,  fertility,  nervous  symptoms,  longevity,  or  the 
development  of  ophthalmia,  scurvy  or  beri-beri.  The  criteria 
for  the  interpretation  of  the  experimental  results  were  such  as 
not  to  require  the  services  of  a  pathologist.  The  pathologist 
was,  however,  unable  satisfactorily  to  comprehend  the  theory 
underlying  the  preparation  of  diets  for  inducing  specific  condi- 
tions profitable  for  study,  and  could  not,  even  if  he  desired  to 
do  so,  accomplish  anything  in  this  field  without  the  aid  of  the 
experienced  physiological  chemist.  With  efficient  cooperation 
between  specialists  in  these  lines  we  may  confidently  expect  new 
and  surprising  relations  to  be  brought  out  in  future. 

Wason  (28)  has  recently  studied  the  pathology  of  ophthalmia 
of  dietary  origin,  but  was  not  able  to  secure  any  fundamental 
data  concerning  the  etiology  of  this  condition.  She  observed  in 
the  eyes  of  rats  in  which  the  disease  was  induced  by  selective 
fasting  for  fat-soluble  A,  hyalinization  or  necrosis  of  the  outer 
layer  of  corneal  epithelium,  exudation  of  serum  and  cells  into 
epithelium  and  stroma,  and  a  proliferation  of  blood  vessels  and 
fibroblasts.  In  advanced  cases  invariably  the  anterior  and  oc- 


270     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

casionally  the  posterior  chamber  were  invaded.  "The  type  and 
virulence  of  the  organisms  of  secondary  infection  determine,  in 
part  at  least,  the  course  of  the  disease." 

Cramer  (29)  reported  an  interesting  study  of  the  relation  of 
fasting  for  fat-soluble  A  to  changes  in  the  histological  structure 
in  certain  adipose  tissue,  which  he  designates  as  "glandular." 
Several  histologists  have  recognized  that  adipose  tissue  in  cer- 
tain parts  of  the  body,  especially  the  subpleural  tissue,  the  neck 
and  interscapular  region,  the  axillae  and  around  the  kidneys, 
presents  a  pink  and  lobulated  appearance  resembling  a  fresh 
pancreas,  and  differs  markedly,  therefore,  from  ordinary  adipose 
tissue  and  can  be  recognized  macroscopically.  This  tissue  is 
histogenetically  distinct  from  ordinary  adipose  tissue.  It  has 
been  described  under  a  variety  of  names  such  as  "primitive  fat 
organ/'  "fat  gland,"  "hibernating  gland,"  "brown  fat"  and  "in- 
terscapular fat."  This  fat  has  in  the  embryo  a  characteristic 
gland-like  structure,  and  in  certain  species,  as  the  white  rat, 
domestic  mouse  and  the  hibernating  animals,  retains  this  struc- 
ture throughout  life.  In  most  species,  according  to  Cramer, 
soon  after  birth  the  tissue  acquires  the  appearance  of  ordinary 
adipose  tissue. 

This  "glandular"  adipose  tissue  is  very  vascular  and  is  dis- 
tinct from  the  ordinary  form  in  its  function.  Many  of  its  cells 
are  polygonal,  present  a  reticulated  appearance,  and  contain 
numerous  small  globules  of  lipins  surrounding  a  nucleus,  in  con- 
trast to  ordinary  fat  cells  which  are  oval,  and  generally  contain 
one  large  fat  globule  engorging  the  cell  and  pushing  the  nucleus 
and  protoplasm  to  one  side.  The  "glandular"  adipose  tissue 
appears  to  contain  a  larger  proportion  of  anisotropic  or  doubly 
refracting  lipins  than  ordinary  fatty  tissue.  The  cells  of  the 
former  are  much  richer  in  protoplasm  than  the  common  type  of 
adipose  cells. 

During  fasting  the  "glandular"  type  tends  to  persist  and  shows 
no  obvious  diminution  whereas  the  ordinary  type  of  adipose  tis- 
sue is  rapidly  and  greatly  diminished.  In  cretins  there  are  cir- 
cumscribed swellings  of  the  "glandular"  adipose  tissue  in  the 
neck  and  axillae,  and  there  appears  to  be  an  hypertrophy  of  this 
tissue  when  the  thyroid  gland  atrophies,  suggesting  a  functional 
relationship  between  them.  Cramer  points  out  also  that  there 
is  evidence  of  such  a  relation  between  the  "glandular"  adipose 
and  the  adrenals.  There  appears  to  be  a  particularly  close  rela- 
tionship between  the  lipins  of  this  tissue  and  those  of  the  adrenal 
cortex. 


CHEMICAL  STUDIES  OF  FAT-SOLUBLE  A        271 

When  rats  are  fed  a  diet  of  purified  food  substances,  free  from 
all  vitamins,  this  "glandular"  tissue  loses  all  its  fat  and  lipins 
and  presents  the  appearance  of  a  glandular  organ.  Under  the 
same  conditions  there  is  a  great  reduction  of  the  lipins  of  the 
cortex  of  the  adrenals,  but  this  never  becomes  entirely  free  from 
them  unless  death  occurs.  Under  the  influence  of  such  a  nutri- 
tive disturbance  the  ordinary  adipose  tissues  lose  all  their  fat 
and  other  lipins  and  revert  to  the  connective  tissue  type  of  cells. 
Cramer  suggests  that  the  "glandular"  adipose  tissue  is  a  reser- 
voir of  fat-soluble  A,  since  the  disappearance  of  the  character- 
istic lipins  from  it  and  the  adrenal  cortex  is  followed  by  death. 


BIBLIOGRAPHY 

1.  Steenbock,  H.,  and  Gross,  E.  G.:     Fat-soluble  vitamine.    ii.  The  fat- 

soluble  vitamine  contents  of  roots  together  with  some  observations 
on  their  water-soluble  vitamine  content,  Jour.  Biol.  Chem.,  1919, 
xl,  501. 

2.  Steenbock,  H.,  and  Boutwell,  P.  W.:     Fat-soluble  vitamine.    iii.  The 

comparative  nutritive  value  of  white  and  yellow  maizes,  Jour.  Biol. 
Chem.,  1920,  xli,  81. 

3.  McCollum,  E.  V.,  Simmonds,  N.,  and  Pitz,  W.:     The  supplementary 

dietary  relationship  between  leaf  and  seed  as  contrasted  with  com- 
binations of  seed  with  seed,  Jour.  Biol.  Chem.,  1917,  xxx,  13. 

4.  Osborne,  T.  B.,  and  Mendel,  L.  B.:     The  vitamines  in  green  foods, 

Jour.  Biol.  Chem.,  1919,  xxxvii,  187;  Ibid,,  1919,  xxxix,  29;  Ibid., 
1920,  xli,  451. 

5.  Steenbock,   and    Gross:      Fat-soluble    vitamine.     iv.   The    fat-soluble 

vitamine  content  of  green  plant  tissues  together  with  some  obser- 
vations on  their  water-soluble  vitamine  content,  Jour.  Biol.  Chem., 
1920,  xli,  149. 

6.  Drummond,    J.    C.:     Researches    on    fat-soluble    accessory    substance. 

1.  Observations  upon  its  nature  and  properties,  Biochem.  Jour.,  1919, 
xiii,  81. 

7.  Steenbock:     White  corn  vs.  yellow  corn  and  a  probable  relation  be- 

tween the  fat-soluble  vitamine  and  yellow  plant  pigments,  Science, 
1919,  1,  352. 

8.  Steenbock,  H.,  Boutwell,  P.  W.,  and  Kent,  H.:     Fat-soluble  vitamine. 

1.  Jour.  Biol.  Chem.,  1918,  xxxv,  517. 

Steenbock,  and  Boutwell :  Fat-soluble  vitamine.  vi.  The  extractability 
of  the  fat-soluble  vitamine  from  carrots,  alfalfa,  and  yellow  corn  by 
fat  solvents,  Jour.  Biol.  Chem.,  1920,  xlii,  131. 

9.  Drummond,  J.  C.,  and  Coward,  K.  H.:     The  nutritive  value  of  animal 

and  vegetable  oils  and  fats  considered  in  relation  to  their  color, 
Biochem.  Jour.,  1920,  xiv,  668. 

Drummond,  J.  C.,  and  Rosenheim,  O.:     The  relation  of  lipochrome 
pigments  to  the  fat-soluble  accessory  food  factor,  Lancet,  1920,  1,  862. 
10.  Stevenson,  M.:     A  note  on  the  differentiation  of  the  yellow  plant  pig- 
ments from  the  fat-soluble  vitamine,  Biochem.  Jour.,  1920,  xiv,  715. 


272     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

11.  Palmer,  L.  S.,  and  Kennedy,  C.:  The  relation  of  the  plant  carotinoids 
to  growth  and  reproduction  of  the  albino  rat,  Jour.  Biol.  Chem.,  1921, 
xlvi,  559. 

12  Palmer,  L.  S.:    Carotinoids  and  fat-soluble  A,  Science,  1919,  1,  501. 

13.  Dolly,  H.,  and  Guthrie,  F.:     The  origin  of  the  nerve  cell  pigments, 

Science,  1919,  1,  190. 

14.  Palmer,  L.  S.,  and  Kempster,  H.  L.:     The  influence  of  specific  feeds 

and  certain  pigments  on  the  color  of  the  egg  yolk  and  body  fat  of 
fowls,  Jour.  Biol.  Chem.,  1919,  xxxix,  299. 

15.  McCollum,   E.    V.,    and    Davis,    M.:      Further    observations    on   the 

physiological  properties  of  the  lipins  of  the  egg  yolk,  Proc.  Soc. 
Exp.  Biol.  and  Med.,  1914,  xi,  101. 

16.  Osborne,    and    Mendel:      Further    observations    on   the    influence    of 

natural  fats  upon  growth,  Jour.  Biol.  Chem.,  1915,  xx,  379. 
Ophthalmia  and  Diet,  Jour.  Amer.  Med.  Assoc.,  1921,  Ixxvi,  905. 

17.  Steenbock,  Boutwell,  and  Kent:     Fat-soluble  vitamine.    1.    Jour.  Biol. 

Chem.,  1918,  xxxv,  517. 

18.  Steenbock,  and  Boutwell:     Fat-soluble  vitamine.     v.  Thermostability 

of  the  fat-soluble  vitamine  in  plant  materials,  Jour.  Biol.  Chem., 
1920,  xli,  163. 

19.  Hopkins,  F.  G.:    The  effects  of  heat  and  aeration  upon  the  fat-soluble 

vitamine,  Biochem.  Jour.,  1920,  xiv,  725. 

20.  Drummond,   and   Coward:     The   effect   of  heat  and   oxygen   on  the 

nutritive  value  of  butter,  Biochem.  Jour.,  1920,  xiv,  734. 

21.  McCollum,   Simmonds,    and    Pitz:      The    dietary   deficiencies    of   the 

maize  kernel,  Jour.  Biol.  Chem.,  1916-17,  xxviii,  153. 

22.  Steenbock,  and  Boutwell:     Fat-soluble  vitamine.     vi.     The  extracta- 

bility  of  the  fat-soluble  vitamine  from  carrots,  alfalfa,  and  yellow 
corn  by  fat  solvents,  Jour.  Biol.  Chem.,  1920,  xlii,  131. 

23.  McCollum,  and  Davis:     The  influence   of  certain  vegetable  fats  on 

growth,  Jour.  Biol.  Chem.,  1915,  xxi,  179. 

24.  Osborne,  and  Mendel:     The  extraction  of  fat-soluble  vitamine  from 

green  foods,  Proc.  Soc.  Exp.  Biol.  and  Med.,  1918-19,  xvi,  98. 

25.  McCollum,  and  Davis:     Observations  on  the  isolation  of  the  substance 

in  butter  fat  which  exerts  a  stimulating  influence  on  growth,  Jour. 
Biol.  Chem.,  1914,  xix,  245. 

26.  Steenbock,  H.,  Sell,  M.,  and  Buell,  M.:     Fat-soluble  vitamine.     vii. 

The  fat-soluble  vitamine  and  yellow  pigmentation  in  animal  fats 
with  some  observations  on  its  stability  to  saponification,  Jour.  Biol. 
Chem.,  1921,  xlvii,  89. 

27.  McCollum,  and  Simmonds:     Unpublished  data. 

28.  Wason,  I.   M.:     Ophthalmia  associated  with  a  dietary  deficiency  in 

fat-soluble  vitamine  (A) :     A  study  of  the  pathology,  Jour.  Amer. 
^  Med.  Assoc.,  1921,  Ixxvi,  908. 

29.  Cramer,  W.:     On  glandular  adipose  tissue  and  its  relation  to  other 

endocrine  organs  and  to  the  vitamine  problem,  Brit.  Jour.  Exper. 
Pathol.,  1920,  1,  184. 


CHAPTER  XIII 
THE  RELATION  OF  PELLAGRA  TO  DIET 

300.  Early  History  of  Pellagra. — Pellagra  is  a  disease  of 
man  which  is  confined  to  relatively  few  places.    It  was  discovered 
in  Northern  Spain  by  Casal  in  1735  (1),  but  for  many  years  it 
was  most  common  in  parts  of  Italy.    Aside  from  Italy  and  Spain, 
pellagra  has  been  prevalent  during  the  last  century  in  parts  of 
France,  the  Balkans,  especially  Roumania,  and  for  a  lesser  time 
in  Egypt.     It  has,  still  more  recently,  afflicted  many  people  in 
the  United  States.    In  this  country  the  disease  was  not  recog- 
nized with  certainty  until  1908,  but  from  that  year  its  incidence 
rapidly  increased  until  by  1917  there  were  recorded  170,000  cases 
of  pellagra,  principally  located  in  the  southern  states. 

301.  Pellagra  Symptoms. — Pellagra  is  a  disease  involving  the 
nervous  system,  the  digestive  tract  and  the  skin.    Usually  one 
of  the  first  symptoms  is  soreness  and  inflammation  of  the  mouth 
followed  by  the  appearance  of  remarkably  symmetrical  erythema 
on  parts  of  the  body.    The  nervous  symptoms  are  more  or  less 
pronounced,  and  become  gradually  worse  as  the  disease  pro- 
gresses.   The  spinal  cord  is  especially  the  seat  of  injury,  but 
the  central  nervous  system  is  also  involved  in  many  instances. 

302.  Theories  as  to  its  Cause. — Several  views  have  been 
proposed  to  explain  the  etiology  of  this  disease.    Marzari,  more 
than  a  century  ago  expressed  the  belief  that  pellagra  resulted 
from  the  excessive  use  of  maize  as  food.    Italian  investigators 
later  accepted  the  view  that  it  was  caused  by  eating  mouldy 
maize,  the  symptoms  being  caused  by  a  toxic  substance  produced 
during  the  spoilage  of  the  grain.    Two  other  theories  have  been 
advanced  to  account  for  its  etiology:  one  that  it  is  caused  by  an 
infecting  organism,  and  the  other  that  it  is  in  some  way  related 
to  faulty  diet.    None  of  these  views  have  been  established  by 
entirely  satisfactory  evidence,  but  the  data  now  point  incon- 
trovertibly  to  a  relation  between  the  diet  and  pellagra.     One 
group  of  investigators  believes  that  pellagra  is  an  infectious  dis- 
ease, but  admits  that  lowered  vitality  from  faulty  nutrition  is  a 

273 


274     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

very  important  predisposing  factor.  Another  group  holds  that 
the  syndrome  results  from  the  lack  in  the  diet  of  a  specific  pro- 
tective substance,  and  that  it  is,  therefore,  analogous  to  beri-beri 
and  scurvy.  Since  almost  all  students  of  this  disease  are  now 
agreed  that  there  is  some  relation  between  the  character  of  the 
diet  and  susceptibility  to  it,  the  present  chapter  will  be  limited  to 
a  discussion  of  the  evidence  of  the  role  of  nutrition  as  an  eti- 
ological  factor  in  pellagra.  Roussel  (2)  as  early  as  1845  stated 
that  the  most  effective  treatment  of  pellagra  is  a  milk  diet. 
Lussana  and  Frua  (3)  in  1856  studied  the  effect  of  improve- 
ment of  the  diet  of  pellagrins,  and  reported  that  they  reduced 
the  mortality  in  about  8,000  cases,  from  24.5  to  4.5  per  cent, 
and  that  they  increased  the  rate  of  recovery  from  20  to  70  per 
cent.  The  idea  that  the  disease  could  be  prevented  or  cured 
by  proper  diet  dates  back  many  years. 

In  1909  the  American  investigators  Wussow  and  Grindley  (4) 
emphasized  the  fact  that  the  diet  of  the  insane  patients  under 
their  observation  was  mostly  composed  of  vegetable  products, 
and  that  it  had  an  especially  low  content  in  animal  protein.  In 
the  light  of  what  has  been  said  in  earlier  chapters  about  the 
specific  dietary  properties  of  the  different  kinds  of  vegetable 
and  animal  food-stuffs,  which  can  be,  to  a  truly  remarkable  ex- 
tent, correlated  with  their  biological  function,  we  are  able  to 
appreciate  the  fact  that  a  fairly  satisfactory  diet  can  be  pre- 
pared from  vegetable  foods  supplemented  with  small  amounts 
of  products  of  animal  origin  provided  the  selection  of  the  articles 
which  enter  into  the  diet  be  a  fortunate  one.  At  the  time  of 
the  investigations  referred  to,  however,  the  significance  of  the 
proper  selection  of  food  for  the  promotion  of  well-being  was  not 
at  all  appreciated. 

303.  Goldberger's  Studies  on  the  Relation  of  the  Diet  to 
Pellagra. — In  1914  Goldberger  (5)  began  an  investigation  of  the 
factors  operating  in  the  etiology  of  pellagra.  His  studies  have 
proven  of  the  greatest  significance  in  clearing  up  this  problem. 
He  noted  the  fact  that  in  several  institutions  where  pellagra 
was  either  epidemic  or  endemic  among  the  inmates,  the  physi- 
cians, nurses  and  attendants  were  almost  without  exception  im- 
mune to  the  disease.  This  indicated  that  contact  with  persons 
suffering  from  pellagra,  or  opportunity  for  transmission  by  bed- 
bugs, with  which  such  institutions  are  almost  always  infested,  did 
not  seem  a  satisfactory  explanation  for  the  transmission  of  the 
disease.  In  institutions  where  the  food  purchases  were  assumed 


THE  RELATION  OF  PELLAGRA  TO  DIET         275 

to  be  alike  for  patients  and  attendants,  it  was  pointed  out  by 
Goldberger,  that  the  diets  of  the  two  groups  were  not  com- 
parable. The  nurses  and  attendants,  due  to  their  favorable 
position,  chose  the  best  articles,  and  diverted  certain  foods  to 
their  own  table  where  the  amounts  did  not  suffice  for  all.  The 
patients  were  thus  placed  at  a  disadvantage  in  regard  to  the 
quality  of  their  food.  Thus  where  the  meat  and  milk  purchased 
for  an  insane  asylum  was  inadequate,  the  tendency  would  be 
for  the  milk  and  the  desirable  cuts  of  meat  to  find  their  way  to 
the  table  of  the  attendants,  while  the  unattractive  pieces  of  fat 
or  gristle  would  be  served  to  the  patients.  Physicians,  nurses 
and  attendants  were  also  in  a  position  to  supplement  the  in- 
stitutional diet  in  any  manner  they  saw  fit. 

Goldberger  gained  the  impression  after  an  examination  of  the 
character  of  the  dietaries  of  certain  institutions  where  pellagra 
was  of  common  occurrence,  that  more  cereals  and  vegetables 
were  used  than  in  the  dietaries  of  people  in  better  financial  cir- 
cumstances who  were  practically  immune  to  the  disease.  This 
led  him  to  undertake  a  study  of  the  possibility  of  preventing  the 
disease  in  institutions  by  improving  the  dietary. 

At  that  time  nothing  was  understood  of  the  peculiar  nutritive 
properties  of  the  different  natural  food-stuffs.  These  have  be- 
come known  through  the  systematic  studies  of  individual  foods 
by  means  of  the  biological  method  introduced  in  1915  by  Mc- 
Collum  and  Davis  (6).  Goldberger  could  therefore  do  nothing 
better  than  to  conclude  that  by  comparing  the  diets  of  persons 
who  developed  pellagra,  with  those  of  people  living  in  the  same 
region  but  remaining  free  from  the  disease,  he  could  arrive  at  a 
conclusion  as  to  the  kind  of  modification  of  the  former  type 
which  should  be  necessary  to  test  the  relation  of  the  diet  to  the 
incidence  of  pellagra.  It  was  apparent  to  him  that  the  habitants 
who  remained  free  from  the  disease,  took  a  diet  which  contained 
much  greater  quantities  of  fresh  meats,  eggs  and  milk,  than  those 
among  whom  the  incidence  was  high.  The  well-to-do  part  of 
the  population  maintained  a  distinctly  better  dietary  through- 
out the  year  than  did  the  poorer  people,  who  with  the  seasons 
suffered  much  greater  changes  in  their  food  supply.  The  winter 
diet  of  the  latter  would  naturally  be  simpler  and  more  monoton- 
ous than  one  which  would  be  available  for  a  moderate  expendi- 
ture of  money  during  the  summer  months.  The  recognition  of 
the  importance  of  seasonal  variations  in  the  diet  as  an  etiological 
factor  in  pellagra  was  one  of  great  importance.  It  is  true,  how- 


276     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

ever,  that  while  pellagra  is  in  great  measure  confined  to  the 
poorer  classes,  and  afflicts  those  who  live  in  the  less  desirable 
parts  of  cities  and  villages,  this  is  by  no  means  always  the  case, 
for  it  occurs  among  the  well-to-do,  but  much  less  commonly 
than  among  those  who  depend  upon  a  daily  wage.  As  will  be 
seen  later,  this  can  best  be  accounted  for  as  due  to  idiosyncra- 
sies which  lead  the  patients  to  make  a  faulty  selection  of  foods. 

304.  The  Investigations  of  the  Robert  M.  Thompson 
Commission,  and  the  Thompson-McFadden  Commission. — In 
1913  the  Thompson-McFadden  Commission,  consisting  of  J.  F. 
Siler  of  the  U.  S.  Army;  P.  E.  Garrison  of  the  U.  S.  Navy,  and 
W.  J.  MacNeal  of  the  New  York  Post  Graduate  Medical  School, 
began  an  extensive  epidemiological  study  of  pellagra  in  Spartan- 
burg  County,  S.  C.  They  collected  a  large  amount  of  data  re- 
garding the  nature  of  the  diets  of  pellagrins.  The  information 
was  obtained  from  statements  of  physicians,  patients,  store- 
keepers, millers,  neighbors  and  others. 

In  their  first  years  of  study  no  satisfactory  data  was  secured 
relating  to  the  diets  of  the  non-pellagrous  portion  of  the  popu- 
lation, but  the  tentative  conclusion  of  the  Commission  was  that 
their  observations  upon  the  habitual  use  of  the  more  common 
food-stuffs,  failed  to  disclose  any  points  of  difference  between 
the  pellagrous  and  non-pellagrous  portions  of  the  population. 
Their  investigations  in  succeeding  years,  which  were  extended  to 
include  an  examination  of  the  dietaries  of  non-pellagrins  tended 
to  confirm  their  belief  that  there  is  no  relation  between  the 
character  of  the  diet  and  the  incidence  of  the  disease  (7). 

Goldberger  has  pointed  out  (8)  that  data  relating  to  diet  to  be 
of  value  in  such  epidemiological  studies,  must  be  secured  with 
individuals,  either  pellagrins  or  non-pellagrins,  and  not  be  of  a 
general  nature,  applying  merely  to  the  family  group.  It  must 
be  kept  in  mind  that  the  changes  in  the  diet  with  the  seasons 
may  be  of  the  greatest  importance.  He  also  pointed  out  that  the 
condition  which  it  is  necessary  for  the  subject  to  reach  before 
a  diagnosis  of  pellagra  would  be  made,  should  be  carefully 
stated.  Much  of  the  conflicting  data  and  resulting  conflict  of 
views  based  on  the  study  of  experimental  data  can  be  explained 
through  failure  of  investigators  to  appreciate  these  facts.  It 
is  in  part  due  to  the  full  appreciation  of  these  points  by  Gold- 
berger, which  gives  his  studies  a  superior  value. 

The  Thompson-McFadden  Commission  came  to  the  conclusion 
as  the  result  of  several  years  of  observation  that  "pellagra  spread 


THE  RELATION  OF  PELLAGRA  TO  DIET        277 

from  a  preexisting  case  as  a  center  in  the  six  villages  studied," 
and  that  "pellagra  morbidity  was  higher  in  congested  commu- 
nities using  surface  privies  than  in  more  sparsely  settled  districts 
in  which  similar  methods  for  the  disposal  of  excreta  were  em- 
ployed." Further,  "...  the  endemic  foci  of  pellagra  were  lo- 
cated in  the  districts  in  which  surface  privies  were  in  use."  In 
two  cotton  mill  villages  completely  equipped  with  a  water- 
carriage  system  of  sewage  disposal  it  was  impossible  to  find  cases 
of  pellagra  which  had  certainly  originated  there,  although  some 
cases  which  had  originated  elsewhere  were  present.  It  was 
decided  that  the  stable  fly  (Stomoxys  calcitrans)  displayed  cer- 
tain salient  characteristics  which  seemed  to  qualify  it  for  the 
role  of  a  transmitter  of  pellagra  (9) . 

305.  The  Studies  of  Jobling  and  Peterson  on  Pellagra  in 
Nashville. — Jobling  and  Peterson  (10)  arrived  from  their  studies 
of  the  disease  in  Nashville  at  a  similar  conclusion  as  to  the 
transmissibility  of  pellagra.  They  were  led  by  their  observa- 
tions to  conclude  that  the  disease  attacked  those  who  were  domi- 
ciled in  parts  of  the  city  which  were  either  without  sewage  dis- 
posal or  where  it  was  inadequate.  Pellagra  could  be  correlated 
with  unscreened  houses,  and  access  of  flies  to  human  excreta 
and  to  human  habitations. 

With  regard  to  diet,  they  stated  that  the  inhabitants  of  the 
South  consume  excessive  amounts  of  carbohydrates  and  fats, 
but  pointed  out  that  in  Nashville  the  people  of  the  class  in 
which  pellagra  occurred  most  frequently,  eat  during  the  spring 
and  summer,  a  great  deal  of  potatoes,  fruits  and  other  fresh 
foods.  This  led  them  to  the  belief  that  pellagra  cannot  be  due 
to  a  deficiency  of  a  "vitamin"  in  the  sense  that  beri-beri  is. 
They  stated  in  this  connection:  "It  seems  strange,  if  this  theory 
is  correct,  that  pellagra  should  be  so  rare  in  winter  when  green 
foods  are  scarce,  and  so  frequent  in  the  spring  and  summer 
when  green  foods  and  fruits  are  plentiful  and  cheap."  Gold- 
berger  felt  that  this  very  fact  that  the  scarcity  of  fresh  fruits 
and  vegetables,  especially  green  foods,  in  winter,  was  significant 
as  an  argument  in  favor  of  the  hypothesis  that  the  disease  was 
the  result  of  a  faulty  diet.  It  is  reasonable  to  suppose  that  any 
effect  on  health  which  might  follow  the  adherence  to  a  faulty 
diet,  would,  under  such  circumstances,  appear  at  the  end  of 
winter,  and  the  effect  of  a  more  satisfactory  diet  in  spring  and 
summer  would  not  necessarily  become  apparent  for  a  time  in 
persons  who  had  been  seriously  injured  by  several  months  re- 


278      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

striction  to  a  faulty  diet.  It  may  require  several  months  to 
induce  scurvy  or  beri-beri  in  man  through  the  agency  of  a 
defective  diet,  and  recovery  is  slow,  even  when  the  diet  is  modi- 
fied so  as  to  contain  everything  which  is  physiologically  essential. 

306.  The  Eradication  of  Pellagra  from  Institutions  by  Mod- 
ification of  the  Diet. — Goldberger,  Waring  and  Willett  (11),  in 
1915,  studied  the  conditions  which  might  explain  the  differences 
in  the  incidence  of  pellagra  in  two  groups  of  children  in  an 
orphanage  at  Jackson,  Miss.  In  this  institution  there  were 
children  from  infancy  to  twelve  years  of  age.  The  presence 
of  pellagra  was  practically  confined  to  the  group  between  the 
ages  of  six  and  twelve  years.  This  was  correlated  with  differ- 
ences in  the  diets  of  the  two  groups  with  respect  to  the  content 
of  fresh  meat  "and  other  animal  protein,"  the  older  group  being 
denied  these  special  articles  of  diet.  Analogous  conditions  were 
discovered  at  other  institutions. 

It  was  the  suggestion  gained  from  earlier  studies  on  beri-beri 
which  led  Goldberger  and  his  co-workers  to  reason  from  analogy 
that  pellagra  was  in  some  way  either  prevented  or  cured  by  some 
specific  substance  or  substances  contained  in  fresh  protein  foods. 
With  this  idea  in  mind  they  instituted  an  experiment  to  test 
whether  pellagra  could  be  prevented  or  cured  by  a  proper  diet. 
The  experiment  was  carried  out  at  two  orphanages  and  an  insane 
asylum.  It  was  not  possible  at  that  time  to  interpret  as  satis- 
factorily as  can  now  be  done,  the  nature  of  the  faults  in  a  diet. 
Goldberger  could,  therefore,  do  no  better  than  to  add  to  the 
institutional  diets  liberal  amounts  of  each  of  the  more  important 
articles  such  as  fresh  meat,  eggs  and  milk,  and  fresh  vegetables, 
since  the  institutional  diets  differed  from  the  better  class  Ameri- 
can diets  in  the  absence  of  these  foods. 

In  one  of  the  two  orphanages  under  observation  during  1914, 
there  was  no  recurrence  of  pellagra  in  any  of  the  67  persons 
afflicted,  who  were  under  surveillance  at  least  until  the  anni- 
versary of  their  attack.  Among  99  pellagrin  residents  of  this 
institution  who  were  under  observation  for  at  least  a  year  there 
was  not  a  single  case  of  the  disease  after  the  change  in  the  diet 
of  the  institution.  At  the  other  orphanage  105  pellagrins  were 
observed  for  at  least  a  year,  including  the  anniversary  of  their 
attack,  and  there  was  not  a  single  case  of  recurrence.  Sixty- 
nine  individuals  who  had  not  suffered  from  the  disease  were 
observed  for  at  least  a  year  and  among  these  not  a  single  case 
developed. 


THE  RELATION  OF  PELLAGRA  TO  DIET        279 

At  the  Georgia  State  Asylum,  which  was  an  endemic  focus 
of  pellagra,  the  diet  of  two  wards  was  modified  so  as  to  greatly 
improve  it,  but  no  change  was  made  in  hygienic  or  sanitary 
conditions.  In  these  two  wards  72  patients  suffering  from  pel- 
lagra during  1914  were  kept  under  observation  at  least  beyond 
the  anniversary  of  their  last  attack,  but  not  one  of  them  showed 
any  sign  of  recurrence.  During  the  corresponding  period  47  per 
cent  of  32  control  patients  in  another  ward  showed  definite  recur- 
rences. The  conclusion  drawn  by  Goldberger  and  his  asso- 
ciates was  that  pellagra  can  be  prevented  by  an  appropriate  diet, 
even  when  the  hygienic  conditions  are  unfavorable. 

307.  An  Attempt  to  Produce  Pellagra  Experimentally  in 
Man  by  Faulty  Diet. — Having  convinced  himself  that  pellagra 
could  be  prevented  by  a  suitable  dietary,  Goldberger  planned 
an  experiment  to  determine  whether  a  faulty  diet  of  the  type 
common  among  pellagrins  would  produce  the  disease  in  man. 
The  plan  involved  restricting  men  to  a  diet  similar  to  those 
which  had  been  supplied  to  the  institutions  where  pellagra  had 
been  endemic,  and  where  it  had  been  relieved  by  the  changes  in 
the  food  supply  described  above.  This  was,  indeed,  the  type 
of  diet  characteristic  of  the  homes  of  the  cotton  mill  workers 
throughout  the  section  of  the  South  where  pellagra  was  very 
common.  This  experiment  is  of  extraordinary  interest  because 
of  the  care  with  which  it  was  planned  and  executed,  and  because 
of  the  unquestioned  skill  of  the  observers. 

The  Governor  of  Mississippi  was  induced  to  offer  pardon  to 
any  of  the  healthy  white  men  in  the  state  prison  who  would 
submit  themselves  as  subjects  of  experiment.  Twelve  men  of- 
fered themselves  and  of  this  group  eleven  actually  underwent 
the  test.  White,  male  adults  were  selected  because  this  group 
of  the  population  in  pellagrous  districts  had  shown  a  lower  in- 
cidence of  the  disease  than  any  other  race,  sex  or  age.  It  was 
believed  that  the  experiment,  if  it  was  successful  in  inducing 
pellagra  in  these  men,  would  be  the  more  conclusive  because 
carried  out  with  this  selected  group  of  subjects. 

The  fact  that  attacks  of  pellagra  occur  most  frequently  in 
the  spring  and  early  summer,  was  also  taken  into  account,  and 
the  experiment  was  started  at  a  season  of  the  year  when,  if 
pellagra  was  successfully  produced  after  a  period  corresponding 
approximately  to  the  winter  season,  during  which  the  people 
of  the  South  restrict  themselves  to  a  simple  and  monotonous 
diet,  the  disease  would  appear  out  of  season,  i.  e.,  in  the  autumn. 


280     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

The  men  were  placed  on  the  experimental  diet  on  April  19,  1915, 
and  continued  with  it  until  October  31st  of  the  same  year. 

The  experiment  was  carried  out  on  the  Rankin  farm  of  the 
Mississippi  penitentiary.  On  this  farm  were  a  considerable 
number  of  convicts  who  were  regarded  as  sufficiently  trustworthy 
to  be  permitted  to  work  on  the  farm  in  some  capacity.  These 
men  were  under  observation  as  controls.  The  time  during  which 
these  men  were  observed  varied  greatly,  but  eight  were  observed 
for  periods  of  eight  to  nine  months.  Of  one  hundred  and  eight 
convicts  on  the  farm  at  the  beginning  of  the  experiment,  thirty 
were  present  until  it  was  terminated.  No  case  of  pellagra  oc- 
curred on  the  farm  during  the  experiment,  or  had  been  noted 
among  the  convicts  or  attendants  at  the  institution  in  previous 
years,  although  it  was  fairly  prevalent  in  the  country  surround- 
ing. There  would  seem  to  be  no  question  of  the  fact  that  the 
eleven  experimental  subjects  were  entirely  protected  against 
exposure  to  pellagra,  for  they  were  under  guard  throughout  the 
experiment. 

The  diet  of  the  men  in  the  experimental  group  consisted  of 
white  wheat  flour,  degerminated  corn  meal  (maize),  polished 
rice,  starch,  sugar,  molasses,  pork  fat,  sweet  potatoes,  collards, 
turnip  greens  and  coffee.  From  the  data  furnished  by  Dr.  Gold- 
berger,  I  calculated  that  less  than  4  per  cent  of  the  total 
energy  value  of  the  diet  was  derived  from  cabbage,  collards, 
turnip  greens  and  sweet  potatoes.  The  diet  was,  therefore, 
essentially  derived  from  degerminated  cereals,  and  products 
made  from  these,  together  with  molasses  and  fat  pork.  It  will 
be  recalled  that  it  has  been  thoroughly  demonstrated  that  such 
a  diet  is  not  adequate  for  the  maintenance  of  health  in  an  adult 
for  a  very  long  period.  The  average  protein  intake  was  41-54 
grams;  of  fat,  91-134  grams,  and  of  carbohydrates,  between  387 
and  513  grams  per  man  per  day  (12). 

At  the  end  of  five  and  a  half  months  six  of  the  eleven  men 
were  diagnosed  as  showing  the  skin  lesions  characteristic  of 
incipient  pellagra.  The  diagnosis  was  concurred  in  by  a  number 
of  dermatologists  who  were  familiar  with  pellagra.  The  first 
evidence  of  skin  eruption  was  seen  on  all  the  men  who  be- 
came affected,  as  a  bilaterally  symmetrical  scrotal  eruption. 
Erythema  appeared  on  the  backs  of  the  hands  of  two  of  the 
men,  and  gastro-intestinal  and  nervous  symptoms  were  noted  in 
all.  Goldberger  and  Wheeler  (12)  hold  the  view  that  it  is  prob- 
able that  the  first  appearance  of  skin  lesions  in  their  experi- 


THE  RELATION  OF  PELLAGRA  TO  DIET        281 

mental  men  on  the  scrotum,  is  to  be  looked  upon  as  the  result  of 
some  peculiarity  in  the  diet  employed.  They  regard  it  as  prob- 
able that  the  several  clinical  manifestations  of  pellagra,  such  as 
the  appearance  of  the  initial  lesions  on  the  back  of  the  hands, 
or  back  of  the  feet,  as  due  to  specific  peculiarities  in  the  diet 
which  brought  on  the  pathological  state.  Thus  they  suggest 
that,  although  their  group  of  subjects  was  served  the  same  diet, 
they  did  not  all  eat  the  same  proportions  of  different  foods. 
Some  traded  dishes,  and  so  one  may  have  eaten  more  green  leafy 
foods;  another  more  sweet  potatoes,  etc.  On  this  basis  they 
would  account  for  the  fact  that  one  man  lost  much  weight  during 
the  experiment  (124  to  99.5  Ibs.),  whereas  another  lost  much 
less  (126-118  Ibs.),  during  the  same  interval.  The  idea  that 
there  is  in  such  a  condition  as  pellagra  an  intimate  relationship 
among  the  several  components  which  go  to  make  up  the  diet, 
and  the  specific  clinical  manifestations  which  the  disease  may 
assume,  involves  a  degree  of  specificity  in  the  effects  of  faulty 
diet,  which  has  as  yet  scarcely  been  acknowledged  by  investi- 
gators. 

308.  Attempts  to  Produce  the  Syndrome  of  Pellagra  in 
Animals. — Attempts  to  produce  the  syndrome  of  pellagra  in 
animals  by  confinement  to  faulty  diets  have  not  been  wanting. 
Chittenden  and  Underbill  (13)  fed  dogs,  exclusively  on  vegetable 
foods,  and  observed  that  they  did  not  thrive.  One  diet,  consist- 
ing of  crackers  (bolted  wheat  flour),  peas  and  cotton-seed  oil, 
produced  in  dogs  restricted  to  it  for  several  months,  a  condition 
regarded  by  these  investigators  as  strikingly  suggestive  of  pel- 
lagra in  man.  The  animals  developed  inflammation  of  the  mouth 
with  sloughing  of  the  mucosa,  diarrhea,  and  skin  changes  of  a 
nature  regarded  as  analogous  to  those  seen  in  pellagra. 

McCollum  and  his  co-workers  had  by  this  time  applied  the 
biological  method  for  the  analysis  of  a  food-stuff  to  all  the  more 
important  cereals  and  legume  seeds.  Their  results  showed  that 
a  diet  of  peas,  wheat  flour  and  cotton-seed  oil  such  as  Chittenden 
and  Underhill  had  employed,  could  be  supplemented  with  puri- 
fied protein,  mineral  salts  and  fat-soluble  A,  so  as  to  be  made 
adequate  for  the  maintenance  of  growth  and  health  in  the  rat. 
After  the  appearance  of  the  paper  of  Chittenden  and  Underhill, 
McCollum,  Simmonds  and  Parsons  (14)  tested  this  theory  by 
feeding  the  diet  of  Chittenden  and  Underhill  supplemented  with 
purified  food-stuffs  in  various  ways  to  young  rats.  The  results 
justified  the  prediction  that  these  three  types  of  corrections 


282      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

were  all  that  was  necessary  to  make  the  diet  complete,  for  the 
rat.  From  these  results  they  drew  the  conclusion  that  the  diet 
used  by  Goldberger  and  his  associates  could  not  possibly  be  defi- 
cient in  any  unidentified  dietary  essential  analogous  to  the  anti- 
neuritic  or  anti-scorbutic  substances.  At  that  time  there  was 
not  available  as  there  is  to-day  a  demonstration  of  the  fact  that 
one  species  of  animal  may  have  decidedly  different  nutritive 
requirements  than  another,  with  respect  to  at  least  one  of  these 
dietary  factors.  The  classic  example  of  this  is  seen  in  the  rat 
which  does  not  require  the  anti-scorbutic  substance,  and  which 
is  incapable  of  developing  scurvy,  whereas  the  guinea  pig  is 
very  susceptible  to  this  disease.  It  no  longer  seems  warranted 
to  assume  that  because  the  rat  does  not  suffer  injury  from  con- 
finement to  a  certain  diet,  that  this  is  sufficient  evidence  that 
the  diet  is  complete  for  another  species.  The  possibility  remains 
that  man  may  require  a  substance  for  protection  against  pel- 
lagra, which  the  rat  is  able  to  synthesize  or  to  dispense  with. 
Further  investigations  are  required  to  settle  this  question. 

McCollum,  Simmonds  and  Parsons  (14)  were  inclined  to  in- 
terpret their  results  as  supporting  the  view  that  pellagra  is  an 
infectious  disease,  and  that  the  role  of  diet  in  its  etiology  in- 
volves only  increased  susceptibility  to  infection  due  to  lowered 
resistance  caused  by  faulty  diet  persisted  in  during  the  winter 
months  by  many  people  in  the  South.  Their  results  supported 
incontrovertibly  the  contention  of  Goldberger,  that  the  type 
of  diet  which  he  fed  to  the  prison  squad  was  incomplete,  and 
would  lead  to  steady  loss  of  vitality,  and  they  made  clear  the 
exact  nature  of  the  deficiencies  of  the  prison  dietary  in  so  far 
as  they  relate  to  the  nutrition  of  the  rat. 

309.  Attempts  to  Transmit  Pellagra  to  Healthy  Subjects. 
— Goldberger  and  fifteen  of  his  associates  next  tried  in  a  num- 
ber of  ways  to  transmit  pellagra  to  themselves  by  a  series  of 
innoculations  with  blood,  nasopharyngeal  secretions,  feces,  urine 
and  desquamating  epithelium.  The  results  of  this  heroic  experi- 
ment were  entirely  negative.  Not  a  single  one  of  the  volunteers 
showed  any  evidence  of  the  disease.  These  subjects  were  all 
presumably  nourished  on  a  satisfactory  diet  previous  to  and 
during  the  experiment,  and  this  could  be  interpreted  as  evidence 
in  support  of  the  view  that  pellagra  is  a  disease  of  low  virulence, 
and  that  it  is  liable  to  attack  only  that  portion  of  the  population 
which,  for  one  reason  or  another,  has  suffered  a  lowering  of 
resistance  (15). 


THE  RELATION  OF  PELLAGRA  TO  DIET         283 

310.  The  Maize  Theory  of  Pellagra  Brought  up  Again. — 
The  Director  of  Medical  Services  of  the  Egyptian  Expeditionary 
Force  directed  that  a  committee  of  medical  men  in  the  British 
Army  make  a  study  of  the  prevalence  of  pellagra  among  Turkish 
prisoners  of  war   (16).    This  report  was  made  by  Boyd  and 
Lelean,  who  concluded  that  the  maximum  distribution  of  pel- 
lagra appeared  to  correspond  geographically  to  the  broad  belts 
where  maize  grew  best,  and  hence  formed  the  larger  proportion 
of  food  in  the  classes  most  pellagrous.    They  attributed  pellagra 
to  starvation  for  protein,  especially  to  a  low  intake  of  pro- 
tein  of  low  biological  value.    It  was  believed  that  on  this 
theory  the  frequent  occurrence  of  pellagra  among  those  who  ate 
mouldy  maize  could  be  explained  by  a  lower  utilization  of  the 
proteins  of  spoiled  grain  than  of  unspoiled.    The  occurrence  of 
pellagra  among  those  who  had  never  eaten  maize  could  be 
explained   as   a   consequence   of  their   securing  through    some 
dietetic  error  a  protein  supply  of  low  biological  value. 

311.  Voegtlin's  Treatment  of  Pellagra  with  Vitamin  Prep- 
arations.— Yoegtlin  (17)  has  recently  described  experiments  in 
the  treatment  of  pellagra,  which  seem  to  fall  little  if  any  short 
of  a  demonstration  that  pellagra  is  a  deficiency  disease  in  the 
same  sense  as  beri-beri  or  scurvy.    This  investigator  has  been 
one  of  the  most  careful  students  of  the  etiology  of  the  disease. 
In  1914  (18)  he  made  the  first  attempt  to  interpret  the  nature  of 
the  deficiencies  of  the  diets  which  are  common  among  those 
classes  of  people  of  the  United  States  among  whom  pellagra  is  of 
frequent  occurrence.    He  proposed  (1)  a  deficiency  or  absence  of 
certain  "vitamins";  (2)  the  presence  of  some  toxic  substances; 
(3)  a  deficiency  in  certain  amino-acids.    Later  researches,  espe- 
cially those  of  McCollum  and  Simmonds  have  shown  that  the 
articles  which  entered  into  the  diet  used  by  Goldberger,  can- 
not contain  sufficient  amounts  of  toxic  substances  to  account 
for  the  ill-effects  observed  when  animals  are  restricted  to  them 
singly    or    collectively.     Concerning    the    other    two    proposed 
explanations  for  pellagra,  both  are  still  debatable  contributing 
factors. 

In  1914  Voegtlin  tested  on  over  one  hundred  patients  in  the 
pellagra  hospital  at  Spartanburg,  the  effects  of  two  types  of 
diets  on  the  clinical  condition  of  the  disease  (18).  Patients  with 
a  moderate  attack  of  pellagra  uncomplicated  by  any  other  dis- 
ease, were  placed  upon  a  diet  which  closely  resembled  that  which 
they  were  accustomed  to  before  the  attack.  These  will  be  desig- 


284      THE  NEWER  KNOWLEDGE  OF  NUTRITION 


Diet  X  consisted  of  the  following  in- 


This  diet  contained  50.5  grams  of 
protein;  89.8  grams  of  fat;  350.8 
grams  of  carbohydrate,  and  yielded 
2473  calories  of  energy. 


nated  as  diets  X  and  Y. 
gredients : 

Wheat  bread   300  grams. 

Butter    30  " 

Cabbage    100  " 

Corn  meal  (maize)   50  " 

Ham  25  " 

Hominy    75 

Corn  syrup   75  " 

Pork   50  " 

Potatoes  150  " 

Prunes   30  " 

Turnip  tops  100  " 

Sugar    40  « 

Milk  .                   40  " 


Of  the  effect  of  restricting  pellagra  patients  to  this  diet  Voegt- 
lin  says:  "Almost  without  exception  the  general  clinical  condi- 
tion of  these  patients  remained  either  stationary  or  gradually 
became  more  aggravated  simultaneously  with  an  increase  in  the 
pellagrous  manifestations.  The  skin  lesions  often  spread  to 
parts  of  the  body  which  had  not  been  affected  previously;  there 
was  also  an  increase  in  the  stomatitis  and  the  gastro-intestinal 
symptoms.  The  appetite,  as  a  rule,  was  good  for  the  first  few 
weeks,  but  diminished  gradually.  The  nervous  manifestations, 
such  as  disturbances  in  sensation,  reflexes,  and  mentality  either 
showed  no  change  or  increased  in  severity.  A  few  cases  de- 
veloped an  acute  psychosis.  A  careful  examination  of  the  dietary 
record  showed  that  the  patients  had  consumed  sufficient  food." 
The  patients  were  changed  after  a  time  to  diet  Y,  the  composi- 
tion of  which  was  given  as  follows: 

Wheat  bread  300  grams. 

Butter   45 

Corn  meal   50 

Eggs    100 

Meat    100 

Orange  juice  100 

Potatoes    150      " 

Prunes   30      " 

Sugar    40      " 

Milk  .  ..1000     " 


This  diet  contained  102.9  grams  of 
protein;  115.3  grams  of  fat;  316.2 
grams  of  carbohydrates,  and  fur- 
nished 2781  calories  of  energy. 


On  diet  Y,  which  differed  from  diet  X  in  containing  4  eggs,  100 
grams  of  fresh  beef  and  one  liter  of  milk  (somewhat  more  than 
one  quart),  the  patients  showed  gradual  improvement,  ending 
in  many  cases  in  the  complete  disappearance  of  all  recognizable 


THE  RELATION  OF  PELLAGRA  TO  DIET        285 

manifestations  of  the  disease.  Another  group  of  patients  which 
was  placed  on  diet  Y  immediately  upon  their  admission  to  the 
hospital,  showed  definite  improvement  within  two  weeks. 
Within  two  months  the  patients  were  judged  to  have  recovered 
from  the  disease,  except  in  a  relatively  few  cases  in  which  it  was 
far  advanced.  Some  of  these  did  not  show  any  benefit  from  the 
improved  dietary. 

Voegtlin  next  placed  patients  on  diet  X  for  a  time  until  it  was 
observed  that  their  clinical  condition  remained  stationary  or 
grew  gradually  worse.  Some  were  then  given  one  of  the  follow- 
ing extracts  of  natural  food-stuffs: 

(1)  A  fat-free,  alcoholic  extract  of  yeast  or  rice  polishings. 

(2)  A  fat-free  alcoholic  extract  of  ox  liver  or  thymus  gland. 

The  first  of  these  extracts  was  chosen  because  it  contained 
a  great  abundance  of  the  anti-beri-beri  substance,  water-soluble 
B.  The  second  contained  a  relative  abundance  of  fat-soluble  A 
and  water-soluble  B.  The  results  indicated  that  the  adminis- 
tration of  extracts  of  yeast  or  rice  polishings  did  not  modify  the 
course  of  the  disease  in  patients  maintained  on  diet  X,  with  the 
possible  exception  of  one  case  in  which  certain  well-marked  nerv- 
ous symptoms  disappeared  coincident  with  the  treatment. 
Voegtlin  states  that  "the  administration  of  the  liver  preparation 
to  pellagrins  was  followed  by  an  improvement  in  their  condition, 
apparently  comparable  to  that  produced  by  the  consumption  of 
a  diet  containing  a  considerable  amount  of  milk,  eggs  and  meat. 
The  evidence  so  far  available,  therefore,  indicates  that  the 
dietary  defect  presumably  responsible  for  pellagra  is  distinctly 
different  from,  and  probably  more  complex  than  the  one  caus- 
ing human  beri-beri." 

If  these  results  are  confirmed  by  further  experiments  it  is 
difficult  to  see  any  other  interpretation  which  can  be  placed 
upon  them  than  that  pellagra  is  a  specific  deficiency  disease, 
due  to  the  lack  of  some  substance  or  substances  which  are  not 
abundant  in  the  articles  which  entered  into  the  composition  of 
diet  X,  but  were  more  abundant  in  milk,  eggs  and  meat,  at  least 
in  liver.  Voegtlin  does  not  imply  that  pellagra  is  necessarily 
due  to  a  deficiency  of  the  diet  in  a  specific  substance  such  as  a 
hypothetical  pellagra  "vitamin,"  proposed  by  Funk.  He  holds 
rather  that  the  pellagrous  syndrome  is  caused  by  a  combination 
of  the  deficiencies  in  some  of  the  well-recognized  food  factors. 


286      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

312.  Voegtlin's  Results  Indicate  Vitamin  Deficiency. — I  am 
unable  to  see  the  logic  of  Voegtlin's  reasoning.  An  alcoholic 
extract  of  liver  would  not  modify  the  inorganic  content  of  diet  X, 
nor  the  biological  value  of  its  proteins.  The  content  of  diet  X  in 
the  anti-neuritic,  anti-scorbutic  and  fat-soluble  A  factors,  when 
compared  with  ordinary  standards,  would  seem  to  be  moderately 
satisfactory.  Poor  quality  of  protein  and  relative  shortage  of 
the  anti-scorbutic  substance  were  the  two  deficiencies  which 
anyone  familiar  with  modern  nutrition  studies  would  suggest 
on  inspecting  the  formula  of  this  diet.  The  extract  of  liver 
would  contain  an  abundance  of  two  at  least  unidentified  dietary 
factors,  but  would  not  improve  the  diet  in  respect  to  the  two 
known  deficiencies.  For  the  rat,  at  least,  it  is  certain  that 
diet  X  would  be  supplemented  by  the  addition  of  purified  protein 
and  mineral  salts,  so  as  to  be  entirely  adequate  for  nutrition  of 
young  animals  during  growth,  and  for  the  maintenance  during 
many  months  of  fairly  good  vigor  in  the  adult.  For  this  species, 
therefore,  there  is  no  necessity  for  postulating  the  need  of  a 
supplementary  addition  of  a  hypothetical  anti-pellagra  sub- 
stance. It  seems  that  if  liver  extracts  are  found  so  effective  in 
supplementing  the  diet  on  which  the  condition  of  patients  re- 
mained stationary,  or  grew  worse,  the  explanation  to  which  one 
must  be  tentatively  driven  is  that  Funk's  hypothesis  that  pel- 
lagra is  actually  a  specific  deficiency  disease  must  be  correct. 
Certain  it  is,  however,  that  Voegtlin  is  illogical  in  trying  to  hold 
simultaneously  to  two  views,  viz.:  that  there  is  something  in  an 
alcoholic  extract  of  fat-free  liver  which  cures  pellagra,  when  it 
is  made  to  supplement  diet  X,  and  that  the  syndrome  is  caused 
by  a  combination  of  the  deficiencies  in  some  of  the  well-recog- 
nized food  factors. 

In  the  preparation  of  the  liver  and  thymus  extracts  Voegtlin 
and  his  co-workers  extracted  the  dried  glands  with  alcohol  at 
room  temperature,  and  after  filtration  a  considerable  part  of 
the  alcohol  was  evaporated  at  35°-40°  C.  in  vacuo.  The  viscous 
substance  remaining  was  extracted  twice  with  ether  in  a  sepa- 
ratory  funnel.  Three  layers  formed:  an  upper  layer  consisting 
of  ether  containing  fats  and  lipins;  a  middle  layer  consisting  of 
white  or  yellowish  insoluble  residue,  and  a  lower  layer  consisting 
of  a  mixture  of  substances  of  oil-like  properties.  The  last- 
named  layer  was  designated  as  the  "vitamin  fraction."  In  the 
treatment  of  adult  pellagra  patients,  daily  doses  of  this  oily 
material  equivalent  to  one  kilogram  of  fresh  liver  or  thymus  were 
administered. 


THE  RELATION  OF  PELLAGRA  TO  DIET        287 

313.  Occurrence  of  Pellagra  in  Nursing  Infants. — Voegtlin 
and  Harries  (19)  have  reported  a  number  of  cases  of  pellagra 
in  infants  which  were  nursed  by  pellagrous  mothers,  and  cite 
older  literature  which  shows  that  in  the  past  a  considerable  num- 
ber of  cases  of  pellagra  have  been  observed  in  infants.    The 
cases  observed  by  Voegtlin  and  Harries  were  observed  in  the 
light  of  all  the  accumulated  knowledge  of  recent  years  concern- 
ing the  relation  of  the  disease  to  faulty  diet,  and  are  therefore 
of  special  importance  in  revealing  the  cause  of  this  condition. 

314.  Report  of  Cases  of  Pellagrous  Mothers  Nursing  Babies 
Who  Did  Not  Develop  the  Disease. — A  mother  suffering  from 
severe  pellagrous  lesions  was   admitted  to  the  hospital  while 
nursing  a  seven-months-old  infant.    The  child  did  not  show  any 
symptoms  of  the  disease.    The  mother  was  placed  upon  the  fol- 
lowing diet  (Diet  A)  during  her  stay  of  35  days  in  the  institution. 
This  diet  is  of  a  type  commonly  used  by  pellagrins. 

DIET  A. 

Breakfast. — Hominy,  75  grams;  butter,  15  grams;  corn  syrup, 
30  grams;  wheat  bread,  100  grams;  coffee,  with  20  grams  of 
sugar  and  20  c.c.  of  milk. 

Dinner. — Potatoes,  150  grams;  cabbage,  50  grams;  turnip  tops, 
50  grams;  fat  pork,  30  grams;  wheat  bread,  100  grams. 

Supper. — Corn  meal  mush,  fried  in  pork  fat,  50  grams;  lean 
boiled  ham,  25  grams;  prunes,  30  grams;  wheat  bread,  100  grams; 
coffee,  with  20  grams  of  sugar  and  20  c.c.  of  milk. 

Samples  of  milk  were  secured  from  this  patient,  and  from  four 
others  who  were  restricted  to  the  same  diet.  These  were  anal- 
ysed by  the  most  approved  chemical  methods  for  all  constituents 
which  can  be  determined  by  such  methods.  The  lactose,  fat, 
total  nitrogen  and  total  solids  were  found  to  fall  within  normal 
limits,  but  were  below  the  average  in  amounts.  The  total  ash 
and  phosphorus  content  were  normal,  but  the  sodium  and  chlorin 
content  were  above  the  normal,  whereas  the  calcium,  magnesium 
and  potassium  were  present  in  amounts  below  the  normal.  No 
tests  were  applied  to  show  the  vitamin  content  of  any  of  these 
milks.  Their  total  volume  was  found  to  be  greatly  diminished 
in  many  cases. 

None  of  the  infants  of  five  mothers  suffering  from  somewhat 
severe  symptoms  of  pellagra,  showed  any  signs  of  the  disease. 
It  is  very  difficult  to  in  any  way  correlate  the  occurrence  of  pel- 
lagra in  infants  with  the  character  of  the  milk  of  mothers  who 


288      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

nurse  them,  for  it  would  seem  that  if  any  relation  existed  be- 
tween the  character  of  the  diet  of  a  mother  and  the  causation 
of  her  attack,  the  infants  suckled  by  them  should,  especially 
when  the  symptoms  are  severe,  more  frequently  develop  pellagra. 
On  the  contrary,  pellagra  in  infants  which  are  nursed  by  mothers 
suffering  from  the  disease  is  by  no  means  common.  Such  mothers 
usually  feed  their  infants  on  the  same  food  which  they  themselves 
eat,  when  the  breast  milk  is  too  scanty  to  suffice  for  the  children. 
This  replacement  of  a  considerable  amount  of  mother's  milk  by 
food  which  leads  to  pellagra  in  the  adult  should,  theoretically, 
go  far  toward  causing  the  disease  in  an  infant,  yet  this  result  is 
seldom  observed.  No  one  has  been  able  to  demonstrate  the 
presence  of  anything  toxic  in  the  milk  or  blood  of  pellagrins,  so 
the  theory  that  the  disease  may  be  an  intoxication  has  no  sup- 
port. 

There  can  be  no  reasonable  doubt  that  the  milk  produced 
by  pellagrous  women,  is  in  general  deficient  in  all  three  of  the 
vitamins  which  are  known  to  produce  specific  syndromes,  and 
the  occasional  occurrence  of  pellagra  in  infants  where  the 
mothers  are  suffering  from  this  disease,  could,  on  first  thought, 
seem  best  accounted  for  on  the  assumption  that  it  is  caused 
by  lack  of  a  specific  vitamin.  This  view  receives  support  from 
the  experimental  work  of  Voegtlin  reported  above,  in  which 
pellagrins  were  reported  to  have  been  greatly  improved  by 
"vitamin  preparations"  made  from  liver  or  thymus.  It  would 
seem  logical  that  the  mother  might,  even  when  she  were  so 
severely  starving  for  a  hypothetical  anti-pellagra  vitamin,  as  to 
cause  in  her  a  severe  form  of  the  disease,  still  continue  to  trans- 
fer to  her  milk  such  small  amounts  of  the  substance  in  question 
as  might  be  furnished  in  her  food,  or  be  available  from  her  own 
tissues.  This  idea  is  not  supported  by  analogy  with  the  char- 
acter of  the  milk  produced  by  lactating  females  whose  diets  are 
lacking  in  one  or  another  of  the  factors,  A,  B  or  C,  since  these 
are  not  in  the  milk  unless  supplied  by  the  diet  of  the  lactating 
mother. 

The  last  suggested  hypothesis,  that  when  the  mother  has  pel- 
lagra but  her  nursing  infant  does  not,  protection  is  afforded  the 
latter  through  sacrifice  on  the  part  of  the  mother  for  the  teleologi- 
cal  purpose  of  preserving  her  offspring,  receives  a  severe  blow 
by  the  observation  of  Voegtlin  and  Harries.  They  observed 
an  infant  about  one  year  of  age,  to  develop  severe  symptoms 
which  unmistakably  indicated  pellagra,  although  her  mother, 


THE  RELATION  OF  PELLAGRA  TO  DIET        289 

nursed  her  throughout  this  time,  and  showed  no  evidence  of  the 
disease.  She  was,  however,  obviously  undernourished  and  suf- 
fered from  chronic  indigestion.  No  other  member  of  the  family 
consisting  of  parents  and  four  children  besides  the  patient, 
showed  any  signs  of  pellagra.  This  observation  would  seem  to 
entirely  negate  the  theory  that  the  disease  can  be  explained  as 
being  due  to  lack  of  a  specific  vitamin  in  the  mother's  milk,  for 
she  did  not  have  the  disease.  This  particular  case  would  seem 
to  support  the  view  that  pellagra  is  due  to  an  infection  with 
which  this  child  came  into  contact. 

315.  Vedder's  Interpretation  of  Existing  Data  Relating  to 
the  Cause  of  Pellagra. — Vedder  (20)  has  brought  together  a 
number  of  salient  facts  derived  from  the  observations  of  several 
students  of  pellagra,  and  interprets  them  as  showing  that  "there 
is  a  certain  similarity  between  pellagra  and  other  known  defi- 
ciency diseases,  namely,  beri-beri  and  scurvy,"  and  "much  of 
the  evidence  that  has  been  presented  as  a  proof  of  the  infectious 
nature  of  pellagra  can  be  reasonably  explained  in  accordance 
with  a  deficiency  hypothesis."  He  further  concludes:  "A  defi- 
ciency is  demonstrable  in  the  diets  of  most  pellagrins.  This 
deficiency  appears  to  me  to  result  from  the  too  exclusive  use  of 
wheat  flour,  in  association  with  corn-meal,  salt  meats  and  canned 
goods,  foods  that  are  known  to  be  deficient  in  vitamins." 

Vedder  has  brought  out  some  very  important  points.  "The 
gastro-intestinal  lesions  in  pellagra  and  scurvy  are  analogous." 
Diarrhea,  enteritis,  ulceration  of  the  intestines  and  hemorrhage 
into  the  mucous  membranes  are  observed  in  both  conditions. 
"There  are  similar  nervous  symptoms  in  pellagra  and  scurvy." 
Osier  (21)  states  that  scurvy  is  to  be  differentiated  from  pellagra. 

Suggestive  similarities  exist  between  pellagra  and  beri-beri. 
The  mucous  membranes  of  the  stomach  and  duodenum  may  be 
swollen  and  inflamed,  and  may  present  ecchymoses  and  erosions. 
"Similarities  in  the  lesions  in  the  nervous  system  and  in  the 
symptomatology  referable  to  the  nervous  system  in  pellagra 
and  beri-beri  can  be  distinguished.  The  pathologic  alterations 
that  occur  in  the  cord  in  pellagra  are  profound  and  striking." 
It  has  been  repeatedly  demonstrated  that  in  beri-beri  there  is 
degeneration  of  many  of  the  motor  cells  in  the  cord.  Roberts 
(22)  describes  the  extensive  degenerations  which  have  been  ob- 
served in  the  spinal  cord  in  pellagra.  Vedder  states  "Now,  if 
we  compare  this  picture  (20)  with  the  changes  found  in  the  cord 
in  beri-beri,  we  find  that  beri-beri  is  characterized  by  the  same 


290      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

scattered  degeneration  of  the  fibers  and  similar  changes  in  the 
cells  of  the  cord." 

Vedder  points  out  that  central  neuritie  symptoms  are  very 
common  in  pellagrins,  and  that  exactly  such  changes  in  the  nerv- 
ous system  caused  beri-beri  for  many  years  to  be  regarded  as 
an  intoxication.  "The  fact  that  the  spinal  fluid  in  pellagra  is 
normal,  points  toward  deficiency,  since  it  seems  improbable  that 
such  extensive  changes  in  the  spinal  cord  could  occur  as  the 
result  of  an  infection  without  producing  the  corresponding 
changes  in  the  spinal  fluid.  Even  the  skin  lesions  which  are  so 
characteristic  of  pellagra  may  be  referable  to  changes  in  the 
cord.  Otherwise,  how  can  we  explain  the  marvellous  symmetry 
that  is  practically  the  constant  characteristic  of  this  symptom?" 
These  are  certainly  very  pertinent  questions  to  raise  in  connec- 
tion with  any  decision  as  to  the  nature  of  the  factors  involved 
in  the  etiology  of  pellagra. 

It  is  evident  from  the  discussion  presented  above  of  the  con- 
flicting evidence  which  is  presented  in  the  extensive  literature 
relating  to  pellagra,  that  it  is  not  at  present  possible  to  give 
credence  to  all  the  data  which  appear  to  emanate  from  reliable 
sources,  and  to  be  derived  from  observations  which  seem  to  be 
accurate,  and  formulate  any  satisfactory  theory  concerning  its 
etiology.  Epidemiological,  clinical  and  chemical  methods  have 
alike  failed  to  establish  beyond  question  the  cause  of  the  disease. 

316.  Pellagra  Can  Be  Prevented  by  a  Satisfactory  Dietary 
Regimen. — From  the  standpoint  of  prevention,  the  researches 
in  this  field  have,  however,  been  of  the  greatest  importance.  It 
is  abundantly  established  that  pellagra  is  in  some  manner  caused 
by  faulty  diet,  and  that  the  type  of  diet  which  is  concerned  in 
its  etiology  is  one  derived  largely  from  milled  cereals,  tubers, 
molasses,  syrup  and  fat  pork  (23).  It  is  absolutely  proven  in 
numerous  cases,  that  milk  is  the  most  effective  therapeutic  agent, 
and  that  the  inclusion  of  a  liberal  amount  of  milk,  together  with 
meats,  eggs  and  leafy  vegetables  in  the  diet  will  prevent  the  dis- 
ease. All  authorities  are  agreed  that  there  is  but  one  effective 
method  of  prevention  or  of  treatment  for  pellagra,  viz.,  a  satis- 
factorily constituted  diet. 

Pellagra  afflicts  the  people  of  the  South,  largely  because  they 
are  engaged  in  the  cultivation  of  a  cash  crop  (cotton),  or  in 
its  manufacture.  Under  such  conditions  the  food  supply  is  de- 
rived in  great  measure  throughout  the  year  from  the  grocery 
store,  and  during  the  winter  season,  practically  exclusively  so. 


THE  RELATION  OF  PELLAGRA  TO  DIET        291 

The  grocer,  in  modern  civilized  and  progressive  communities,  has 
come  in  recent  times,  to  restrict  his  line  of  foods  in  great  measure 
to  milled  cereals  and  canned  goods  which  are  derived  either  from 
muscle  meats  or  from  seed  products  (beans,  peas,  corn,  etc) 
and  molasses.  As  has  been  repeatedly  shown  by  experiments  on 
animals,  it  is  not  possible  to  prepare  from  such  a  list  of  foods  a 
diet  which  will  promote  well-being  over  any  prolonged  period. 
On  such  a  diet  ill  health  and  inefficiency  are  to  be  expected,  and 
experience  has  abundantly  shown  that  this  result  is  being  real- 
ized where  such  dietary  practices  prevail. 

The  knowledge  of  the  methods  by  means  of  which  pellagra  can 
be  eradicated  is,  therefore,  quite  adequate,  and  as  soon  as  it  can 
be  applied  practically  where  needed,  the  disease  may  confidently 
be  expected  to  disappear  in  proportion  to  the  extent  to  which 
reform  in  the  diet  of  the  population  can  be  brought  about.  The 
reduction  of  the  consumption  of  milled  cereal  products,  molasses 
and  fats,  and  a  substitution  of  liberal  amounts  of  the  protective 
foods,  milk  and  the  leafy  vegetables  will  free  any  community 
from  this  scourge,  which  is  now  (1921)  reported  to  afflict  more 
than  two  hundred  thousand  people  in  the  United  States. 

BIBLIOGRAPHY 

1.  Casal:    Obra  Postuma  del  Dr.  Casal  Publicada  en  1762,  Corresp.  Med. 

Madrid,  1870,  vol.  v,  78.  Cited  by  Goldberger:  Public  Health 
Reports,  1920,  xxxv,  2673. 

2.  Roussel,   T.:      Traite   de   la   pellagra   et  des   psuedo-pellagras,   Paris, 

1866,  529. 

3.  Lussana,  and  Frua:     Sufla  Pellagra,  Milan,  1856. 

4.  Wussow,  A.  F.,  and  Grindley,  H.  S.:     Report  of  the  biochemical  work 

done  under  the  auspices  of  the  Illinois  Pellagra  Commission,  1911. 

5.  Goldberger,  J.:     The  cause  and  prevention  of  pellagra,  Pub.  Health 

Reports,  Wash.,  D.  C.,  1914,  Sept.  11.    Reprint  No.  218. 
Goldberger:     The  transmissibility  of  pellagra,  Public  Health  Reports, 
Wash.,  D.  C.,  1916,  Nov.  17.     Reprint  No.  376. 

6.  McCollum,  E.  V.,  and  Davis,  M.:     The  essential  factors  in  the  diet 

during  growth,  Jour.  Biol.  Chem.,  1915,  xxiii,  231. 

7.  Siler,  J.  F.,  Garrison,  P.  E.,  and  McNeal,  W.  J.:    A  statistical  study  of 

the  relation  of  pellagra  to  the  use  of  certain  foods,  Arch.  f.  Med., 
1914,  xiv,  292. 
Harris,  H.  F.:     Pellagra.     New  York,  1919. 

8.  Goldberger,  J.,  Wheeler,  G.  A.,  and  Sydenstricker,  E.:     A  study  of 

family  income  and  other  economic  factors  to  pellagra  incidence  in 
seven  cotton-mill  villages  of  South  Carolina  in  1916,  Pub.  Health 
Reports,  Wash.,  D.  C.,  1920,  xxxv,  2673,  Nov.  12. 

9.  Report   of   the   Robert   M.   Thompson   Pellagra   Commission   of  the 

New  York  Post-Graduate  Medical  School  and  Hospital,  1917. 


292      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

10.  Jobling,  J.  W.,  and  Peterson,  W.:     The  epidemiology  of  pellagra  in 

Nashville,  Tenn.,  Jour,  of  Infect.  Dis.,  1917,  xxi,  109. 

11.  Goldberger,  J.,  Waring,  C.  H.,  and  Willets,  D.  G.:     The  prevention 

of  pellagra,  Public  Health  Reports,  Wash.,  D.  C.,  1915,  xxx,  3117. 

12.  Goldberger,  J.,  Wheeler,  G.  A.,  and  Sullivan,   M.  X.:     The   experi- 

mental production  of  pellagra  in  human  subjects  by  means  of  diet, 
U.  S.  Pub.  Health  Service,  Hygienic  laboratory  bulletin  No.  120. 
Feb.  1920.  Pub.  Health  Reports,  Nov.  12,  1915,  3336. 

13.  Chittenden,  R.  H.,  and  Underbill,  F.  P.:  The  production  in  dogs  of  a 

pathological  condition  which  closely  resembles  human  pellagra, 
Amer.  Jour.  Physiol.,  1917,  xliv,  13. 

14.  McCollum,  E.  V.,  Simmonds,  N.,  and  Parsons.    A  biological  analysis 

of  pellagra-making  diets: 

1.  The  dietary  properties  of  mixtures  of  maize  kernel  and  bean, 

Jour.  Biol.  Chem.,  1917,  xxxii,  29. 

2.  The   minimum   requirements   of  the   two   unidentified   dietary 

factors  for  maintenance  as  contrasted  with  growth,  Ibid.,  1917, 
xxxii,  181. 

3.  The  value  of  some  of  the  seed  proteins  for  maintenance,  Ibid., 

1917,  xxxii,  347. 

4.  The  cause  of  failure  of  mixtures  of  seeds  to  promote  growth 

in  young  animals,  Ibid.,  1917,  xxxiii,  303. 

5.  The  nature  of  the   deficiencies  of  a  diet  derived  from  peas, 

wheat  flour,  and  cottonseed  oil,  Ibid.,  1918,  xxxiii,  411. 

15.  Goldberger,   J. :      The   transmissibility   of   pellagra;    experimental   at- 

tempts at  transmission  to  the  human  subject,  Pub.  Health  Reports, 
Wash.,  D.  C.,  Nov.  17,  1916,  xxxi,  3159. 

16.  Boyd,  F.  D.,  and  Lelean,  P.  S.:     Report  of  a  committee  of  enquiry 

regarding  the  prevelance  of  pellagra  among  Turkish  prisoners  of 
war,  Alexandria,  Egypt,  1919.  Also,  Jour.  Roy.  Army  Med.  Corps, 
1919,  xxxiii,  426. 

17.  Voegtlin,  C.:  Recent  work  on  pellagra,  Harvey  Lecture  Series,  1919-20. 

Public  Health  Reports,  Wash.,  D.  C.,  1920,  xxxv,  1435,  June  1920. 
Voegtlin,   C.,  Neill,  M.  H.,  and  Hunter,  A.:     The  influence   of  the 
vitamines  on  the   course   of  pellagra,  U.  S.  Pub.   Health  Service, 
Hyg.  Lab.  Bull.  No.  116,  1920. 

18.  Voegtlin,  C.:     The   treatment  of  pellagra,  Jour.   Amer.   Med.  Assn., 

1914,  Ixiii,  1094. 

19.  Voegtlin,   C.,   and   Harries,   R.   H.:     The   occurrence    of   pellagra    in 

nursing  infants  with  observations  on  the  chemical  composition  of 
human  milk  from  pellagrous  mothers,  U.  S.  Pub.  Health  Service, 
Hyg.  Lab.  Bull.  116,  1920. 

20.  Vedder,  E.  B. :    Dietary  deficiency  as  the  etiological  factor  .in  pellagra, 

Arch.  Int.  Med.,  1916,  xviii,  137. 

21.  Osier,  W.:     The  principles  and  practice  of  medicine,  New  York,  1912. 

22.  Roberts:     Pellagra,  St.  Louis,  1912. 

23.  Siler,  Garrison,  and  MacNeal:     A  statistical  study  of  the  relation  of 

pellagra  to  use  of  certain  foods  and  to  location  of  domicile  in  six 
selected  industrial  communities,  Arch,  of  Int.  Med.,  1914,  xiv,  293; 
Second  progress  report,  1915. 

Goldberger,  Wheeler,  and  Sydenstricker :     A  study  of  the  relation  of 
the   family   income   and   other   economic   factors   to   incidence    of 


FIG.  13. — This  picture  illustrates  the  emaciated  appearance  of  a  middle  aged  rat 
after  being  fed  about  four  months  on  a  diet  consisting  of  bolted  flour,  degerminated  corn 
meal,  rice,  sugar,  starch,  pork  fat,  molasses,  sweet  potato,  and  cabbage.  Such  a  diet  has 
been  reported  by  Gpldberger  to  have  produced  pellagra  in  man  in  five  and  a  half  months. 
This  diet  affords  wide  variety  and  consists  of  wholesome  food  products,  yet  fails  to  main- 
tain normal  nutrition  because  it  contains  too  little  of  the  protective  foods,  milk,  eggs  and 
the  leafy  vegetables. 


,0 

Is 


FIG.  15. — Illustrates  the  skin  lesions  on  the 
arm  and  hand  of  a  pellagrin.—  Courtesy  of 
the  Thompson  Pellagra  Commission. 


THE  RELATION  OF  PELLAGRA  TO  DIET        293 

pellagra  in  seven  cotton-mill  villages  in  South  Carolina  in  1916, 
Pub.  Health  Reports,  Wash.,  D.  C.,  1920,  xxxv,  2673,  Nov.  12. 

Goldberger,  Wheeler,  and  Sydenstricker:  A  study  of  the  relation  of 
diet  to  pellagra  incidence  in  seven  textile  mill  communities  in  South 
Carolina  in  1916,  Pub.  Health  Reports,  Wash.,  D.  C.,  1920,  Mar.  19. 

Goldberger,  Wheeler,  Sydenstricker,  and  Tarbett:  A  study  of  the 
relation  of  the  factors  of  a  sanitary  character  to  pellagra  incidence 
in  seven  cotton-mill  villages  in  South  Carolina  in  1916,  Pub.  Health 
Reports,  Wash.,  D.  C.,  1920,  xxxv,  1701. 

Goldberger,  Wheeler,  and  Sydenstricker:  A  study  of  the  diet  of  non- 
pellagrous  and  of  pellagrous  households,  Jour.  Amer.  Med.  Assn., 
1918,  Ixxi,  944,  Sept.  21. 

Goldberger,  Wheeler,  and  Sydenstricker:  Pellagra  incidence  in  rela- 
tion to  sex,  age,  season,  and  occupation,  Pub.  Health  Reports,  Wash., 
D.  C.,  1920,  xxxv,  1650,  July  9. 

Givens,  M.  H. :  Chemical  analyses  of  the  stomach  contents  of  100 
pellagrins,  Amer.  Jour,  of  Med.  Sci.,  1918,  civ,  221. 

Sullivan,  M.  X.,  and  Jones,  K.  K.:  Biochemical  studies  of  the  saliva  in 
pellagra,  Pub.  Health  Reports,  Wash.,  D.  C.,  1919,  xxxiv,  1068, 
May  16. 


CHAPTER  XIV 

THE  RELATION  OF  THE  DIET  TO  THE  ETIOLOGY  OF 
RICKETS  AND  RELATED  CONDITIONS 

317.  The  Prevalence  of  Rickets  in  Children. — There  are 
probably  no  conditions  which  contribute  more  to  physical  in- 
feriority in  man  than  defects  in  skeletal  development.    Most  im- 
portant among  these  is  the  result  of  a  syndrome  designated  as 
rickets.     This  disease  varies  in  severity,  and  individual  cases 
present,  therefore,  pictures  which  differ  in  some  details,  but  all 
cases  have  certain  characteristics  in  common.   Rickets  leads  to 
deformity,  due  to  abnormal  enlargement  of  the  ends  of  the  bones, 
and  to  distortion  due  to  bending  owing  to  lack  of  resistance  of 
the  bones  to  the  body  weight,  to  muscular  tension  and  to  atmos- 
pheric pressure.    The  latter  factor  is  especially   important  in 
changing  the  form  of  the  thorax.    Bow  legs,  knock  knees,  en- 
larged joints,  flat  or  deformed  chest  and  abnormal  conformation 
of  the  skull,  are  the  result  of  the  failure  of  the  bones  to  develop 
in  a  normal  manner. 

Rickets  is  essentially  a  disease  of  infancy  and  early  childhood, 
although  it  may  under  exceptional  conditions  appear  in  children 
of  five  or  six  years  or  even  later  (rachitis  tarda).  Since  the 
war  this  "late  rickets"  has  become  very  common  in  the  children 
of  central  Europe.  The  disease  may  be  manifest  by  the  second 
month  of  life.  It  is  most  frequent  from  the  seventh  month  to  the 
end  of  the  second  year.  It  is  usually  accepted  as  true  that  the 
disease  is  never  or  only  very  rarely  present  at  birth,  but  since 
clinically  recognizable  symptoms  may  occur  very  early  in  life, 
and  the  development  of  the  disease  is  slow,  it  must  in  many 
children  have  its  beginning  in  the  earliest  days  of  extra- 
uterine  life. 

318.  The  Characteristics  of  the  Disease. — In  many  children 
the  condition  is  only  discovered  at  autopsy  since  the  lesions  have 
not  sufficiently  progressed  during  life  to  attract  attention.     It 
must  be  emphasized  that  although  the  diagnosis  rests  only  upon 

294 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    295 

the  manifestations  in  the  skeleton,  rickets  is  a  disease  of  the 
entire  organism  and  not  of  the  bones  only.  The  children  exhibit 
signs  which  can  only  mean  that  the  whole  body  is  involved  in  the 
physiological  process.  They  are  nervous  and  irritable,  but 
usually  are  apathetic  and  disinclined  to  play.  They  sleep  poorly. 
The  muscles  are  flabby,  wasted  and  weak.  This  is  not  only  true 
of  the  voluntary  muscle  but  also  of  the  smooth  muscle  of  the 
gastro-intestinal  tract.  The  ligaments  are  loose  and  lax.  The 
children  perspire  freely,  especially  about  the  head  (head  sweats) . 
Frequently  the  head  is  continually  rolled  from  side  to  side  on 
the  pillow  so  that  the  hair  may  be  worn  off  from  the  back  of  the 
head.  There  is  often  a  more  or  less  marked  secondary  anemia. 

The  disease  may  exist  without  symptoms.  Those  which  are 
found  result  from  the  abnormality  of  the  bony  structures  and 
the  feebleness  of  the  musculature.  The  children  sit,  stand  and 
walk  at  much  later  periods  than  normal  children.  Although 
they  have  as  much  opportunity  for  exercise  as  the  normal  child, 
they  do  not  profit  by  it.  Weakness  of  the  abdominal  and  intes- 
tinal musculature  results  in  accumulation  of  gas  in  the  intestine, 
and  distention  of  the  abdomen  (pot  belly).  The  teeth  are  late 
in  making  their  appearance  and  decay  early. 

The  bones  are  widely  affected.  Rickets  is  more  severe,  often, 
in  some  bones  than  in  others,  but  in  advanced  cases  every  bone 
in  the  body  is  involved.  Those  that  grow  most  rapidly  suffer 
first.  The  bones  of  the  skull  and  fibs  are  attacked  early.  Among 
the  earliest  signs  of  rickets  are  areas  of  softening  in  the  bones  of 
the  skull  (craniotabes) .  The  junctions  of  the  bony  ribs  with 
their  cartilages  become  enlarged.  The  softened  ribs  are  bent  by 
atmospheric  pressure  and  by  the  traction  of  the  diaphragm  dur- 
ing breathing  so  that  a  deep  groove  is  formed  in  the  chest  wall 
along  the  insertion  of  the  diaphragm.  The  long  bones  become 
bent  and  are  swollen  at  their  extremities.  Bow  legs  and  knock 
knees  and  sabre  shins  result  from  bending  of  the  softened  bones, 
and  the  wrists  and  ankles  are  swollen.  On  the  bones  of  the 
skull  masses  of  soft  tissue  beneath  the  periosteum  give  rise  to  the 
appearance  of  the  so-called  bosses  or  swellings.  The  fontanels 
are  slow  to  close.  In  severe  cases  the  bones  may  fracture  or  the 
head  of  the  bone  may  be  separated  from  the  shaft.  The  spine 
may  be  twisted  and  the  pelvis  distorted.  The  resistance  of  these 
children  to  infections  is  lowered  and  they  have  sometimes  an 
almost  continuous  coryza.  This  lowered  resistance  together  with 
the  deformities  of  the  chest  make  them  very  liable  to  attacks 


296     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

of  bronchitis  or  bronchopneumonia.  which  frequently  are  the 
direct  cause  of  death. 

While  the  death  of  rachitic  children  is  usually  due  to  some 
intercurrent  infection,  severe  rickets  may  be  fatal  of  itself  as 
Park  and  Rowland  (1)  have  pointed  out. 

319.  A  Historical  Survey  of  Rickets. — Findlay  (2)  in  a  re- 
cent historical  survey  of  rickets  says:  "In  this  (England)  as  in 
most  civilized  countries,  rickets  is  one  of  the  most  common  dis- 
eases of  childhood.  Further,  it  is  probably  the  most  potent 
factor  in  interfering  with  the  efficiency  of  the  race.  It  not  only 
stunts  the  growth  and  causes  deformities,  some  of  which  greatly 
increase  the  dangers  of  child-bearing  in  the  female,  but  it  raises 
considerably  the  mortality  rate  of  such  diseases  as  measles  and 
whooping  cough,  and  is  responsible  for  the  rejection  annually  of 
a  not  inconsiderable  number  of  army  recruits." 

Schmorl  (3)  examined  hundreds  of  children  and  found  that 
90  per  cent  of  all  who  died  under  four  years  of  age  had  had 
rickets.  Dick  (4)  reported  that  80  per  cent  of  all  the  children 
in  London  County  Council  Schools  had  had  rickets.  Hess  and 
linger  (5)  found  the  disease  present  in  nearly  all  the  negro 
children  in  the  negro  quarter  of  New  York,  and  they  recently 
state  that  "all  seem  to  agree  that  it  occurs  in  more  than  50  per 
cent  of  the  children  of  the  poor."  Thompson  (6)  reports  that 
more  than  50  per  cent  of  the  children  of  Edinburgh,  London, 
Glasgow  and  Manchester  suffer  from  rickets.  It  will  be  readily 
apparent,  therefore,  that  rickets  constitutes  a  national  health 
problem  of  first  importance. 

Rickets  is  a  disease  which  has  long  afflicted  the  human  race. 
It  was  described  in  its  general  features  by  Soranus  in  the  first 
century  of  the  Christian  Era  (7).  He  stated  that  the  majority 
of  Roman  children  suffered  from  deformity  of  the  spine  and 
crooked  legs,  and  noted  that  this  abnormality  of  growth  was 
more  common  in  the  neighborhood  of  Rome  than  in  other  places. 
He  said  further,  that  the  disease  was  unknown  among  the  Greeks, 
and  attributed  this  to  the  greater  interest  and  care  bestowed 
by  the  Greek  mothers  upon  their  infants,  than  was  customary 
with  the  mothers  of  Rome.  Defects  of  skeletal  development  of 
the  nature  of  rickets  appear  not  to  have  existed  in  Ancient  Egypt. 

Rickets  as  a  clinical  entity  was  first  described  in  some  detail 
by  Francis  Glisson  in  1650  (8) ,  and  his  work  has  become  one  of 
the  classics  of  medical  science.  He  described  the  enlargements 
of  the  ends  of  the  long  bones,  the  deformity  of  the  thorax,  the 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    297 

"rosary"  due  to  enlargement  of  the  junctions  of  the  bony  ribs 
with  their  cartilages,  the  abnormally  large  head,  the  protruding 
abdomen,  the  flacidity  of  the  musculature  and  the  generally 
wasted  condition  of  the  body.  He  pointed  out  that  the  disease 
was  not  usually  fatal,  and  attributed  the  deformity  to  unsym- 
metrical  growth  of  the  two  sides  of  the  bones  because  of  inter- 
ference with  the  blood  supply. 

320.     Geographical    Distribution   of   Rickets. — Findlay    (2) 
points  out  that  rickets  is  almost  entirely  limited  to  the  northern 


dio, 


.cor 


hemisphere,  and  that  it  is  in  great  measure  restricted  to  the  tem- 
perate zone.  At  present  it  is  a  veritable  scourge  among  the 
children  of  many  parts  of  Europe  owing  to  conditions  brought 
about  by  the  war.  It  is  common  in  most  parts  of  Europe  except 
in  southern  Spain,  southern  Italy,  and  Portugal.  It  appears  to 
be  rare  in  the  West  Indies,  most  parts  of  South  America,  the  Phil- 
ippines, a  large  part  of  China,  India  and  the  Malay  peninsula. 
Sporadic  cases  occur  in  all  these  places.  Mellanby  (9)  states 
that  in  the  west  of  Ireland  the  disease  is  unknown.  Rickets  is 
said  to  be  much  rarer  among  Jewish  children  than  among  other 
elements  in  the  population. 


298     THE  NEWER  KNOWLEDGE  OF  NUTRITION 


Worm  a.  I 
Legend  descriptive  of  illustrations  of  normal  and  rachitic  bones, 

shown  on  pp.  297-298. 

To  show  the  differences  between  a  rachitic  and  a  normal  bone. 
In  the  shaft  (dia)  and  the  center  of  ossification  (co)  of  the 
epiphysis  (ep),  calcified  tissue  is  black  and  osteoid  tissue  red. 
The  zone  of  provisional  calcification  is  absent  from  the  rachitic 
bone,  and  the  proliferative  zone  of  cartilage  (pz)  is  prolonged 
as  an  irregular  mass  of  cartilage  which  is  ragged  and  inter- 
digitates  with  tongues  of  osteoid  tissue.  A  metaphysis  is  formed. 
The  cortex  (cor)  is  thickened  though  the  bone  in  it  is  very  thin. 
The  trabeculae  are  surrounded  by  osteoid. 

c Resting  cartilage. 

co Center  of  ossification. 

ep Epiphysis  (head) . 

met Metaphysis. 

dia Shaft  (diaphysis) . 

zc Provisional  zone  of  calcification. 

pz Proliferative  zone  of  cartilage. 

T Trabecula. 

cor Cortex  of  shaft. 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    299 

321.  Rickets  Absent  from  Certain  Parts  of  the  Hebrides. — 

Mellanby  further  calls  attention  to  the  almost  complete  absence 
of  rickets  in  the  Island  of  Lewis  in  the  Hebrides,  although  the 
people  there  live  under  the  most  intolerable  hygienic  conditions. 
He  emphasizes  the  importance  of  this  fact  in  support  of  the 
view  that  the  disease  is  essentially  due  to  faulty  diet,  and  not 
to  unfavorable  hygienic  surroundings. 

It  is  necessary  to  receive  statements  about  the  geographical 
distribution  of  rickets  with  a  certain  amount  of  skepticism,  since 
they  are  often  the  result  of  careless  observation  or  of  the  in- 
ability of  the  observer  to  recognize  mild  cases  of  the  disease. 
The  statement  is  made  frequently  and  accepted  generally  that 
rickets  does  not  occur  in  the  tropics  or  is  very  rare.  As  a  matter 
of  fact  the  disease  is  not  at  all  uncommon  in  parts  at  least  of 
Central  and  South  America  (Brazil,  Venezuela,  Guatemala). 

322.  Views  Concerning  the  Cause  of  Rickets. — The  most 
diverse  views  have  been  advanced  regarding  the  cause  of  this 
disease.    Many  have  believed  it  an  essential  concomitant  of 
civilization.    This  idea  is  supported  by  the  unquestioned  fact 
that  it  is  much  more  common  in  cities  than  in  rural  districts. 
It  is  relatively  rare  to-day  among  the  less  progressive  peoples  of 
the  Orient  and  among  those  of  tropical  and  subtropical  regions. 
It  is  very  significant  from  the  standpoint  of  determining  its 
cause,  that  the  disease  is  .very  rare  or  unknown  in  certain  places 
as  in  Ireland,  and  the  Hebrides,  and  very  prevalent  in  adjacent 
regions,  in  England  and  Scotland,  where  differences  in  climate 
or  in  amount  of  sunlight  could  not  logically  be  invoked  as  factors 
which  would  determine  the  incidence  of  rickets.    In  Iceland  the 
disease  occurs  very  rarely,  and  is  unknown  among  primitive 
Eskimo.    Findlay  states  that  inquiry  of  the  Alaskan  School 
Service  revealed  that  rickets  had  recently  occurred  in  several 
villages  north  of  the  Arctic  circle.     It  was  stated  that  the  natives 
of  these  villages  were  living  under  better  conditions  than  in 
former  years.    Because  of  this  last  statement  Findlay  expresses 
skepticism  about  the  diagnosis.     It  would  seem,  however,  that 
this  "living  under  better  conditions  than  in  former  years,"  may 
have  been  a  very  significant  factor  in  causing  the  appearance 
of  rickets  among  the  children.    This  so-called  improvement  may 
well  have  included,  in  addition  to  living  in  a  house  instead  of 
the  primitive  hut,  a  generous  addition  of  bolted  wheat  flour  and 
other  cereal  products,  and  canned  goods  to  the  diet.    This  point 
would  be  well  worth  further  inquiry. 


300     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

323.  Rickets  Does  Not  Occur  in  Wild  Animals. — Rickets 
does  not  occur  among  wild  animals,  but  is  common  among  wild 
creatures  kept  in  confinement.    This  is  especially  true  of  mon- 
keys and  young  carnivora  kept  in  zoological  gardens.     Dogs, 
especially  the  larger  breeds,  are  very  prone  to  develop  rickets, 
whereas  cats  are  said  to  remain  free  from  the  disease  under 
domestication.    This  fact  is  of  great  significance,  since  the  cat 
rarely  fails,  even  when  domesticated,  to  kill  birds  and  small 
rodents  in  considerable  numbers,  and  to  remain  in  a  measure 
on  the  type  of  diet  characteristic  of  wild  carnivora,  whereas  dogs 
are  less  enterprising  as  foragers,  and  rely  upon  the  food  pro- 
vided by  their  masters.     Herbivorous  animals  such  as  the  horse, 
cow,  sheep,  pigs  and  others  do  not  frequently  exhibit  skeletal 
defects  where  a  pasturage  is  available.     It  will  be  shown  later 
that  these  facts  can  be  satisfactorily  explained  on  the  theory 
that  the  diet  is  the  most  important  factor  in  the  etiology  of 
rickets. 

324.  Relation  of  Breast  Feeding  to  Incidence  of  Rickets. — 
Rickets  was  formerly  much  more  common  among  the  poorer 
classes  than  among  the  well-to-do.    It  occurs  much  more  fre- 
quently in  the  winter  and  spring  than  at  the  other  seasons,  and 
is  much  more  prevalent  among  bottle-fed  infants  than  among 
nursed  infants.     It  occurs  not  infrequently  in  infants  who  are 
breast-fed.    It  is  not  uncommon  to  see  severe  rickets  develop 
in  negro  children  who  are  fed  almost  entirely  at  the  breast.    The 
following  table  from  data  collected  by  Miss  Ferguson  (2)  shows 
the  relation  of  rickets  in  the  children  of  Glasgow  to  length  of 
time  at  the  breast  in  months. 


Marked  Rickets 

Slight  Rickets 

Non-rachitic 

(250  Children) 

(200  Children) 

(200  Children) 

No. 

Per  Cent. 

No. 

Per  Cent. 

No. 

Per  Cent. 

Not  at  all  

58 

23 

32 

16 

25 

12.5 

1  month   

g 

4 

6 

3 

7 

3.5 

2  months  

12 

5 

5 

2.5 

3 

1.5 

3  months  

12 

5 

9 

4.5 

6 

3 

4-6  months  

17 

7 

12 

6 

10 

5 

7-9  months  

17 

7 

25 

12.5 

33 

16.5 

10-12  months... 

54 

21 

57 

28.5 

66 

33 

Over  12  months 

70 

28 

54 

27 

49 

24.5 

Since  breast-feeding  has  been  generally  regarded  in  the  past 
as  assurance  that  the  diet  of  the  infant  will  be  of  satisfactory 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    301 

quality,  data  such  as  are  recorded  in  the  table  on  page  300  would 
be  interpreted  by  most  people  as  a  strong  support  for  the  view 
that  the  character  of  the  diet  has  little  or  nothing  to  do  with  the 
etiology  of  rickets.  In  recent  years,  however,  there  has  been 
brought  to  light  more  and  more  evidence  of  an  experimental 
nature,  which  casts  doubt  upon  the  adequacy  of  breast  milk  as  a 
food,  where  the  diet  of  the  mother  is  not  wisely  chosen. 

The  studies  of  Ferguson  further  emphasize  the  importance  of 
the  time  of  year  in  influencing  the  development  of  rickets.  Of 
349  children  observed  by  her,  232  ceased  to  thrive  between 
December  and  May,  against  117  who  developed  rickets  during 
the  other  half  of  the  year.  Thompson  (6)  has  also  recently 
emphasized  the  effect  of  the  winter  season  in  inducing  this  dis- 
order. 

325.  Some   Regard   Diet,   Others   Hygiene,   as  the  Main 
Factor  in  Inducing  Rickets. — No  unanimity  of  opinion  exists 
among  students  of  rickets  concerning  its  cause.     Heredity,  diet- 
etic errors,  faulty  hygienic  conditions,  infections  of  a  microbial 
or  other  nature,  and  disturbances  of  the  endocrin  glands,  have 
all  been  incriminated  as  the  causative  agents.    At  the  present 
time  two  schools  of  investigators  are  essentially  monopolizing 
the  field  in  the  study  of  this  disease.     One  holds  that  it  is  essen- 
tially a  condition  brought  about  by  errors  in  the  diet,  although 
admitting  that  unfavorable  living  conditions  of  any  kind  may 
play  a  role  in  that  they  depress  the  metabolic  functions  and 
cause  the  child  to  show  more  readily  the  effects  of  faulty  nutri- 
tion than  it  would  under  more  favorable  conditions.    The  other 
school  supports  the  view  that  hygienic  conditions,  especially  lack 
of  sunlight,  and  not  dietetic  factors,  play  the  dominant  role  in 
the  etiology  of  the  disease.     It  seems  possible  to  offer  an  ex- 
planation which  brings  into  harmony  most  of  the  observations 
upon  which  the  diverse  interpretations  have  been  placed. 

326.  Mellanby  Suggests  That  Rickets  Is  Due  to  Lack  of 
Fat-Soluble  A.— In   1919  Mellanby    (9)    reported  experiments 
which  excited  great  enthusiasm  among  investigators  of  nutrition 
problems.    He  was  able  to  show  that  certain  diets  produced  a 
condition  of  the  bones  of  young  puppies  which  he  believed  to  be 
identical  with  rickets  in  the  human  being.     Radiographs  showed 
a  decrease  in  the  density  of  the  bones.    The  ends  of  the  shafts 
were  cupped  and  much  enlarged  and  were  more  or  less  ragged 
in  appearance.    The  translucent  (to  X-rays)   area  between  the 
shaft  and  the  center  of  ossification  in  the  head  of  the  bones  was 
increased  in  depth.    Mellanby  regarded  rontgenograms  of  this 


302      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

sort  as  sufficient  evidence  of  rickets.  As  will  be  made  clear 
later  the  radiograph  only  shows  that  the  bones  were  not  normally 
developed,  but  gives  no  information  concerning  the  exact  nature 
of  the  lesion  such  as  can  be  learned  only  by  histological  exam- 
ination of  stained  sections.  The  most  striking  point  brought 
out  by  his  experiments  was  the  protective  function  of  butter  fat 
and  cod  liver  oil  in  preventing  the  development  of  rickets  or 
some  similar  condition.  One  diet  which  produced  rickets  in 
pups  was  composed  of  skimmed  milk  175  c.c.;  white  bread  ad 
libitufri',  linseed  oil  10  c.c.;  yeast  10  grams,  and  common  salt 
1^-2  grams.  The  addition  of  10-20  grams  of  butter  served  to  so 
improve  the  nutrition  of  the  animals  that  rickets  did  not  develop. 
Mellanby  drew  the  conclusion  from  his  studies,  that  such  fats 
as  furnish  fat-soluble  A  are  protective  against  rickets,  whereas 
vegetable  fats  which  do  not  contain  appreciable  amounts  of  this 
substance,  are  of  little  value  in  this  respect.  He  was  therefore 
inclined  to  identify  the  fat-soluble  A,  or  some  substance  having 
a  similar  distribution,  as  a  specific  anti-rachitic  substance. 

Mellanby  compared  two  diets  which  Ferguson  (2)  had  de- 
scribed as  typical  of  rachitic  and  of  non-rachitic  families  re- 
spectively in  Glasgow.  These  are  so  instructive  that  they  are 
reproduced  here  in  tabular  form.  It  will  be  evident  to  anyone 
who  has  become  familiar  with  the  specific  dietary  properties  of 
the  individual  food-stuffs  and  with  the  nutritive  requirements 
of  an  animal  with  respect  to  calcium,  phosphorus  and  fat-soluble 
A,  and  with  the  importance  of  having  proteins  of  high  biological 
value,  that  one  is  not  justified  in  interpreting  the  results  of 
restricting  human  beings  or  animals  to  one  or  the  other  of  these 
two  types  of  diets,  as  turning  upon  their  content  of  fat-soluble 
A,  or  similar  substance  which  might  play  an  important  role  in 
the  etiology  of  rickets. 

AVERAGE  CONSUMPTION  PER  "MAN"  PER  DAY  OF  THE  CHIEF  ARTICLES  OP 

DIET  IN  GRAMS. 

(1)  RACHITIC  FAMILIES.    (2)  NON-RACHITIC  FAMILIES. 


U) 

Ci) 

ID 

(f) 

Flour          

3879 

3762 

Other  cereals 

156 

269 

Potatoes  . 

2910 

2368 

Margarine  or  butter 

326 

385 

Milk        

2560 

3090 

Fish 

157 

359 

Meat   

89.1 

92.6 

Eggs   . 

151 

304 

Sugar    

91.4 

84.0 

Cheese  

67 

82 

Qfttrneft]    ............ 

40.4 

36.0 

RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    303 

327.  A  Comparison  of  a  Rachitic  and  a  Non-Rachitic  Diet- 
ary.— It  is  very  significant  that  the  quantities  of  milk,  eggs, 
cheese,  fish  and  butter  contained  in  diet  (2)  over  diet  (1)  was 
effective  in  preventing  the  occurrence  of  rickets.    Ferguson  did 
not  consider  the  differences  in  the  composition  of  these  types 
of  diets  sufficient  to  support  the  view  that  the  diet  had  any 
importance  as  a  factor  in  the  production  of  rickets.    When  these 
diets  are  evaluated  in  the  light  of  present  day  knowledge,  it  is 
easy  to  see  that  neither  is  of  very  good  quality  for  the^promo- 
tion  of  growth  or  the  maintenance  of  health,  but  that  diet  (2) 
is  distinctly  better  than  (1).  ~yjp'     t 

A  similar  comment  may  be  made  concerning  the  rachitic  diet 
described  above,  which  became  non-rachitic  on  the  addition  of 
butter.  The  basal  diet  which  induced  rickets  was  poor.  One 
factor  in  which  it  was  distinctly  below  the  optimum  was  its  con- 
tent of  fat-soluble  A.  The  addition  of  this  substance  improved 
the  diet,  not  only  because  of  its  enhancement  in  fat-soluble  A, 
but  because  any  other  defects  in  the  diet  would  become  manifest 
in  the  condition  of  the  animals,  to  a  lesser  degree  when  more  of 
the  needed  fat-soluble  A  was  present.  We  have  already  seen 
that  any  single  factor  in  a  diet  may  be  well  below  the  optimal 
in  quality,  without  its  effects  becoming  apparent.  They  appear, 
however,  when  another  factor  is  reduced  in  quality  so  as  to  in- 
crease the  total  burden  which  the  tissues  must  tolerate,  in  the 
way  of  badly  constituted  nutriment. 

Mellanby's  hypothesis  would  seem  to  derive  support  from 
the  century  long  use  of  cod  liver  oil  as  a  therapeutic  substance 
in  the  treatment  of  rickets  and  from  such  studies  as  those  of 
Schabad  (10),  who  showed  that  the  exhibition  of  cod  liver  oil 
increased  retention  of  calcium  salts  by  the  body. 

328.  Hess  and  Unger's  Experiments  on  Infants  with  Fat- 
Poor  Diets. — After  the  appearance  of  Mellanby's  paper  his  opin- 
ion was  at  once  accepted  as  resting  on  sound  experimental  evi- 
dence.   The  Medical  Research  Committee  of  Great  Britain  ac- 
cepted it  and  gave  it  wide  publicity  in  their  bulletin  (9) .    Hess 
and  Unger  (5),  who  had  earlier  stated  their  view  that  the  long 
accepted  use  of  cod  liver  oil  in  the  therapy  of  rickets  was  based 
upon  sound  experimental  data,  and  that  in  their  experience  it 
had  proven  a  specific  in  the  treatment  of  rickets,  now  came  for- 
ward with  the  publication  of  the  results  of  feeding  experiments 
on  infants  with  diets  very  deficient  in  fat-soluble  A  (11).    The 
diet  consisted  of  dried  skim  milk  180  grams;  dissolved  in  ten 


304      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

times  its  weight  of  water;  to  this  was  added  30  grams  of  cane 
sugar,  15  c.c.  of  orange  juice,  30  c.c.  of  autolyzed  yeast,  and 
30  c.c.  of  cottonseed  oil.  This  was  fed  to  infants  ranging  from 
four  to  nine  months  of  age,  for  a  period  of  five  to  nine  months. 
Growth  at  a  fairly  satisfactory  rate  was  observed,  and  no  evi- 
dences of  rickets  were  apparent.  The  conclusion  was  drawn  that 
fat-soluble  A  is  a  factor  of  minor  importance  in  human  nutrition. 
This  view  is  at  variance  with  the  remarkable  studies  of  Mori 
(12)  and  of  Bloch  (13)  as  well  as  of  those  of  Wells  (14),  which 
leave  no  room  for  doubt  that  butter  fat  and  cod  liver  oil  furnish 
something  which  may  under  acute  conditions  cause  prompt  re- 
covery from  ophthalmia,  brought  on  by  malnutrition. 

The  diet  employed  by  Hess  and  linger  cannot  be  regarded  as 
a  satisfactory  one  to  which  an  infant  may  safely  be  confined, 
notwithstanding  their  observation  that  their  subjects  grew  dur- 
ing the  experimental  period.  There  is  every  reason  to  suppose 
that  they  were  brought  into  a  state  of  nutritional  instability  as 
the  result  of  being  confined  to  the  diet.  This  was  very  satis- 
factorily constituted  except  for  its  shortage  of  fat-soluble  A, 
and  judging  from  experience  with  animals  they  should,  therefore, 
have  been  able  to  tolerate  for  a  considerable  period  this  defect 
in  their  dietary,  but  not  necessarily  without  injury  in  some  de- 
gree. McCollum  and  Davis  (15)  had  shown  that  skim  milk 
powder  contains  approximately  half  the  fat-soluble  A  that  was 
contained  in  the  whole  milk  from  which  it  was  prepared.  Hop- 
kins (16)  has  expressed  a  similar  view  as  the  result  of  his  in- 
vestigations. No  conclusions  are  warranted  from  the  data  of 
Hess  and  linger  other  than  that  young  children  can  live  and 
grow  as  their  graphs  show  them  to  have  done.  They  throw  no 
light  on  the  relation  of  fat-soluble  A  in  its  relation  to  bone 
growth,  or  the  nutritive  needs  of  the  human  infant  for  this 
dietary  factor,  since  their  experimental  diet  was  by  no  means 
so  deficient  in  fat-soluble  A  as  they  supposed  it  to  be. 

Very  recently  Hess  and  linger  (17)  have  abandoned  the  view 
that  rickets  is  due  to  dietary  defects,  and  have  adopted  the  view 
that  hygienic  factors,  especially  sunlight,  play  a  dominant  role 
in  determining  the  seasonal  variation  of  this  disorder.  They 
base  their  belief  upon  the  evidence  afforded  by  rontgen  ray 
pictures,  which  showed  that  illumination  of  infants  suffering 
from  rickets,  with  ultraviolet  rays  from  a  mercury  vapor  lamp, 
caused  the  deposition  of  calcium  phosphate  in  the  zone  of  pri- 
mary calcification  of  the  long  bones.  Hess  and  linger  offer  no 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    305 

explanation  for  the  mechanism  of  the  action  of  cod  liver  oil  as 
a  specific  therapeutic  agent  in  the  treatment  of  rickets  in  their 
earlier  studies. 

329.  Exercise  as  a  Factor  in  Preventing  Rickets  in  Pups. — 
Findlay  (18)  has  continued  as  has  also  Paton  (19),  to  empha- 
size that  the  opportunity  which  is  afforded  for  pups  to  exercise 
is  the  determining  factor  as  to  whether  or  not  they  will  be  likely 
to  develop  rickets.    Recently  these  investigators  have  been  in- 
clined to  accept  infection  as  playing  the  major  role  in  the  pro- 
duction of  rickets. 

It  will  be  evident  to  one  who  gives  careful  scrutiny  to  the 
recorded  experimental  studies  of  this  subject,  that  as  yet  no 
thoroughgoing  research  has  been  carried  out  for  the  purpose  of 
making  clear  the  etiology  of  rickets.  Shipley,  Park,  Simmonds 
and  McCollum  (20)  have  approached  the  problem  from  an  essen- 
tially new  viewpoint.  They  observed  in  the  course  of  extensive 
studies  of  nutrition  problems  with  a  large  rat  colony,  that  cer- 
tain animals  whose  diets  were  faulty  in  one  or  more  respects, 
developed  a  condition  which  presented  the  gross  appearance  of 
rickets  both  as  respects  external  appearance  and  conditions 
which  could  be  observed  at  autopsy.  They  were  convinced  that 
only  by  a  most  elaborate  study  of  the  subject,  that  is,  by  sys- 
tematically varying  the  composition  of  the  diet  with  respect 
to  one  or  more  factors,  and  by  means  of  careful  histological 
studies  of  the  bones  of  their  animals,  could  one  expect  to  reveal 
the  relation  of  the  diet  to  the  disease.  Since  their  animals  were 
all  kept  in  a  north-east  room,  into  which  sunlight  enters  only  in 
small  amount,  and  all  of  the  colony  were  under  essentially  uni- 
form conditions  as  respected  illumination,  temperature,  ventila- 
tion and  opportunity  for  exercise,  they  were  convinced  that  any 
differences  which  could  be  demonstrated  in  the  histological  struc- 
ture of  the  bones  must  be  due  to  the  character  of  their  experi- 
mental diets,  which  formed  the  only  variable.  Radiographs 
cannot  be  of  much  value  in  studies  in  this  kind  since  they  do 
not  reveal  the  nature  of  the  anatomic  changes  which  take  place 
under  experimental  conditions.  These  studies  have  progressed 
far  enough  to  establish  certain  important  facts  concerning  the 
etiology  of  rickets. 

330.  Sequence  of  Events  in  the  Growth  of  Bone. — The 
growth  of  a  bone  in  length  is  due  to  a  definite  sequence  of  events 
which  transpire  at  the  junction  of  the  shaft  of  the  bone   (di- 
aphysis)  with  its  head  (epiphysis).    The  shaft  is  composed  of 


306      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

growing  bone,  the  epiphysis  of  cartilage  which  is  largely  in  a 
resting  state.  As  the  animal  grows  the  cartilage  of  the  epiphy- 
sis is  converted  into  bone  through  (a)  encroachment  on  it 
of  the  bony  shaft  and  (b)  through  the  expansion  of  one  or  more 
centers  of  ossification  which  form  in  it.  The  process  of  growth 
in  length  of  the  shaft  is  the  same  which  results  in  the  expansion 
of  the  centers  of  ossification  in  the  epiphysis. 

The  cells  of  the  resting  cartilage  have  no  particular  arrange- 
ment until  they  come  within  a  short  distance  of  the  shaft  or 
center  of  ossification.  The  cartilage  cells  then  arrange  them- 
selves into  columns  parallel  to  the  long  axis  of  the  shaft  or 
the  radii  of  the  ossification  center.  This  columnar  zone  is  known 
as  the  "proliferative  cartilage."  Lime  salts  are  deposited  in  the 
matrix  separating  the  cells  of  the  thin  layer  of  cartilage  in  con- 
tact with  the  shaft.  This  is  known  as  the  zone  of  provisional 
calcification.  Cartilage  cells  in  this  zone  lie  in  a  matrix  which 
is  like  a  calcified  honey-comb.  As  the  shaft  grows  tiny  blood 
vessels  sprout  evenly  from  it  and  each  vessel  opens  a  single  com- 
partment in  the  calcified  honeycomb.  The  cartilage  cell  is 
freed  to  degenerate  or  to  become  an  osteoblast  or  bone-forming 
cell.  Large  numbers  of  osteoblasts  follow  the  blood-vessel 
sprouts  into  the  cartilage.  These  settle  on  the  spicules  of  cal- 
cified matrix  which  remain  after  the  cartilage  cell  capsules  are 
opened.  These  spicules  furnish  cores  about  which  the  trabeculae 
of  bone  in  the  shaft  are  built.  The  osteoblasts  on  the  spicules 
of  calcified  matrix  bury  themselves  in  a  tissue  known  as  osteoid 
which  they  manufacture.  This  receives  a  deposit  of  lime  salts 
and  becomes  bone. 

Growth  in  thickness  of  the  shaft  is  accomplished  by  cells  in 
a  thick  layer  of  connective  tissue  which  surrounds  the  shaft 
and  is  called  the  periosteum.  These  connective-tissue  cells  are 
transformed  directly  into  osteoblasts  and  lay  down  bone  in 
layers  beneath  the  periosteum.  During  growth,  and  to  a  lesser 
extent  after  growth  has  ceased,  the  structure  of  a  bone  is  sub- 
ject to  constant  change  to  meet  the  requirements  of  exercise  and 
changing  conditions  of  stress  and  strain.  Old  bone  is  constantly 
being  removed  (resorption)  and  new  bone  is  always  being 
formed.  In  a  normal,  healthy  bone  these  processes  are  always 
in  a  dynamic  equilibrium. 

331.  Abnormal  Histological  Changes  in  Rachitic  Bones. — 
In  the  rachitic  bone  all  these  processes  of  growth  and  the  main- 
tenance of  equilibrium  are  abnormal.  Calcium  salts  are  not 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    307 

deposited  in  a  normal  way.  In  a  normal  bone  the  junction  of 
the  cartilage  with  the  shaft  forms  a  straight,  regular  line.  In 
the  rachitic  bone  it  is  ragged  because  there  is  no  provisional  zone 
of  calcification  and  the  cartilage  is  invaded  by  large  tufts  of 
blood-vessels  from  the  shaft  which  destroy  it  irregularly.  At 
the  same  time  masses  of  cartilage  persist  where  they  should  be 
destroyed  and  islands  remain  cut  off  from  the  main  body  of  the 
tissue.  Osteoid  is  not  calcified  as  it  is  formed  either  in  the 
trabecula?  or  by  the  periosteum,  so  that  the  bones  become  soft. 
The  animal  attempts  unsuccessfully  to  compensate  for  the  weak- 
ness due  to  the  lack  of  lime  salts  by  producing  osteoid  tissue 
in  abnormal  amounts,  especially  at  points  subject  to  stress  and 
strain  (the  curved  side  of  the  bone  and  at  the  insertions  of 
muscle  and  tendons).  This  over-production  of  osteoid  and  car- 
tilage causes  irregular  enlargement  of  the  bones  and  their 
weakness  consequent  upon  the  lack  of  lime  salts  results  in  bowing 
and  fracture.  Because  of  the  abnormal  growth  at  the  end  of 
the  shaft  a  zone  known  as  the  rachitic  metaphysis  forms,  which 
consists  of  blood-vessels,  connective  tissue,  osteoid,  marrow  ele- 
ments, and  cartilage  cells  in  all  stages  of  degeneration  and 
change  into  other  tissue.  The  osteoid  formed  shows  little  sign 
of  being  absorbed  in  rickets  as  it  is  commonly  seen.  The  bal- 
ance of  forces  has  swung  in  the  direction  of  apposition  and 
persistence  of  cartilage. 

332.  Recent  Investigations  on  the  Cause  of  Rickets. — The 
investigations  of  Shipley,  Park,  Simmonds  and  McCollum  have 
shown  that  when  the  diet  is  satisfactory  in  every  respect  except 
for  a  deficiency  of  calcium,  the  phosphate  content  and  content 
of  fat-soluble  A  being  near  the  optimal,  changes  take  place  in 
the  skeleton  which  bear  a  fundamental  resemblance  to  rickets 
as  it  occurs  in  the  human  being.  There  is  a  tendency  to  in- 
creased persistence  of  the  proliferative  cartilage  of  the  epiphysis. 
The  cartilage  becomes  invaded  by  blood-vessels  from  the  mar- 
row of  the  shaft.  There  is  failure  to  deposit  calcium  salts  in 
the  intercellular  substance  of  the  cartilage,  which  forms  the 
initial  feature  of  the  process  of  normal  calcification.  A  rachitic 
metaphysis  is  formed.  There  is  likewise  over-production  of 
osteoid  tissue.  The  gross  deformities  in  young  rats  maintained 
on  such  defective  diets  (deficient  only  in  calcium)  cannot  be  dif- 
ferentiated from  those  seen  in  rickets. 

There  are,  however,  decided  differences  in  the  histological 
picture  seen  in  bone  sections  derived  from  animals  selectively 


308      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

fasted  for  calcium  alone,  as  compared  with  those  ordinarily  seen 
in  rickets.  It  has  been  pointed  out  that  normally  the  band  of 
proliferative  cartilage  consists  of  cells  which  are  arranged  in 
columns.  In  true  rickets  this  orderly  arrangement  is  lost,  and 
the  cartilage  cells  become  irregularly  disposed.  In  the  animals 
deprived  of  calcium,  but  supplied  with  all  other  dietary  essen- 
tials in  normal  amounts,  the  orderly  arrangement  of  the  car- 
tilage cells  is  not  disturbed,  notwithstanding  the  formation  of 
abnormal  amounts  of  osteoid,  and  the  development  of  the 
metaphysis.  There  is  also  evidence  that  resorption  of  bone  and 
osteoid  in  the  shaft  is  rapid  under  these  dietary  conditions. 

When  calcium  carbonate,  in  appropriate  amount,  is  added 
to  such  diets  as  produce  the  picture  described  above,  none  of 
the  abnormalities  described  occur.  When,  on  the  other  hand 
cod  liver  oil  is  included  in  the  diets  which  are  deficient  in  cal- 
cium, but  in  no  other  respect,  and  the  deficiency  is  sufficiently 
marked  to  cause  the  rickets-like  condition  to  develop,  the  bones 
remain  essentially  normal  and  no  metaphysis  forms.  When  the 
cod  liver  oil  is  administered  after  the  pathological  changes  due 
to  deprivation  of  calcium  have  developed,  healing  of  the  lesion 
results.  The  calcium  necessary  for  deposition  in  the  zone  of 
primary  calcification  under  these  circumstances  appears  to  be 
borrowed  from  the  shaft,  for  this  becomes  osteoporotic,  or  fragile 
owing  to  resorption  of  its  mineral  salts. 

The  administration  of  butter  fat  instead  of  cod  liver  oil  to 
animals  which  are  deprived  of  a  sufficient  amount  of  calcium, 
does  not  protect  them  in  the  way  that  cod  liver  oil  does.  Even 
large  doses  (20  per  cent  of  the  food  mixture)  exerts  but  a  feeble 
protective  action.  It  must  be  concluded,  tentatively,  therefore, 
that  cod  liver  oil  is  rich  in  some  substance  which  is  intimately 
concerned  with  bone  growth,  which  is  not  abundant  in  butter 
fat,  and  that  the  evidence  available  at  present,  points  to  the 
possible  existence  of  a  separate  dietary  factor  analogous  to  the 
recognized  vitamins,  which  can  be  recognized  by  its  effects  on 
the  changes  in  the  bones  of  animals  which  have  been  prepared 
for  a  period  by  restricting  them  to  diets  which  lead  to  the 
development  of  rickets. 

When  young  rats  are  restricted  to  diets  which  contain  the 
normal  amounts  of  calcium  and  of  phosphate,  a  deficiency  in 
fat-soluble  A  causes  changes  in  the  bone  of  a  pathological  nature. 
This  factor  alone  cannot,  however,  be  responsible  for  the  de- 
velopment of  rickets.  This  statement  also  applies  to  a  relative 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    309 

shortage  of  the  hypothetical  anti-rachitic  factor  which  we  ten- 
tatively suggest  is  distinct  from  fat-soluble  A,  and  abundant  in 
cod  liver  oil.  A  specific  starvation  for  this  substance  cannot 
of  itself  produce  rickets. 

When  in  the  nutrition  of  young  rats,  a  diet  is  employed  which 
is  deficient  in  utilizable  phosphorus  compounds  and  also  in  the 
organic  factor  which  exerts  an  anti-rachitic  effect,  there  is  pro- 
duced a  pathological  condition  of  the  skeleton  which  bears  fun- 
damental resemblances  to  rickets,  but  differs  from  rickets  in 
certain  respects.  The  chief  difference  consists  in  the  presence 
of  scattered  or  irregular  deposits  of  calcium  salts  in  the  metaphy- 
sis  and  cartilage.  The  appearance  of  histological  sections 
of  the  bones  of  these  animals  closely  resembles  those  of  ani- 
mals which  have  suffered  from  rickets  but  in  which  healing  of 
the  lesion  is  in  progress.  The  addition  of  a  suitable  amount 
of  the  phosphate  ion  to  such  a  diet,  the  deficiency  of  the  organic 
factor  still  existing,  results  in  the  prevention  of  the  develop- 
ment of  the  changes  of  a  rickets-like  nature,  though  the  bone  is 
not  normal. 

The  remarkable  effect  of  the  administration  of  cod  liver  oil 
to  animals  which  are  deprived  of  sufficient  calcium,  in  protect- 
ing them  from  the  detrimental  effects  of  such  deficiency — a  pro- 
tection which  is  not  afforded  by  four  or  five  times  the  amount 
of  butter  fat  necessary  to  entirely  meet  the  needs  of  the  growing 
rat  for  fat-soluble  A,  when  its  diet  is  satisfactorily  constituted 
with  respect  to  calcium  and  phosphate,  makes  it  imperative  that 
we  accept  the  view  that  there  is  an  organic  factor  which  exerts 
an  anti-rachitic  effect,  and  is  concerned  in  the  normal  nutrition 
of  the  bones. 

333.  Three  Factors  Operate  in  the  Etiology  of  Rickets. — 
It  will  be  seen  from  the  foregoing,  that  three  dietary  factors  at 
least  are  concerned  primarily  in  the  development  and  normal 
metabolism  of  the  skeletal  tissues.  These  are  the  phosphorus 
and  calcium  content,  and  the  content  of  the  organic  substance 
which  we  may  provisionally  designate  as  the  anti-rachitic  sub- 
stance, although  this  is  not  an  entirely  satisfactory  term  since 
this  substance  is  not  a  preventive  of  rickets  in  the  sense  that 
the  anti-beri-beri  substance  or  the  anti-scorbutic  substance  are 
respectively  preventives  of  beri-beri  and  scurvy.  The  organic 
substance  under  discussion  may  exert  an  anti-rachitic  effect,  but 
so  also  may  phosphorus  or  calcium,  depending  on  the  peculiar 
constitution  of  the  diet. 


310     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Rickets,  it  will  be  seen,  is  not  a  deficiency  disease  in  the  same 
sense  as  are  beri-beri,  scurvy  or  the  ophthalmia  of  dietary  origin. 
Beri-beri,  scurvy  and  ophthalmia,  so  far  as  we  can  now  see,  are 
due  to  specific  starvation  for  one  (possibly  more)  organic  sub- 
stance, peculiar  to  each  disease,  whereas  rickets  has  at  least  three 
etiological  factors,  disturbances  of  the  ratios  among  which  will 
effect  the  structure  of  the  bones. 

It  is  now  easy  to  appreciate,  in  the  light  of  the  experiments 
just  described,  that  rickets  must  be  studied  in  a  special  way  if 
satisfactory  results  are  to  be  secured.  Isolated  observations  can- 
not well  be  correlated  and  interpreted.  It  is  essential  that  the 
effects  on  the  structure  of  the  osseous  system,  of  deviation  from 
the  optimal  relations  with  respect  to  all  factors  which  can  be 
shown  to  enter  into  the  etiology  of  rickets  and  related  disturb- 
ances of  bone  growth,  be  systematically  studied  in  a  very  com- 
prehensive way  before  a  complete  explanation  can  be  given  of 
this  most  interesting  problem  in  pathology. 

334.  The  Ratio  Between  Calcium  and  Phosphorus  in  the 
Diet  is  Very  Important. — A  discovery  of  great  importance  in 
this  connection  was  recently  made  by  McCollum,  Simmonds, 
Shipley  and  Park  (20)  who  observed  that  the  ratio  between  the 
concentration  of  calcium  and  of  phosphorus  in  the  diet  may, 
within  certain  limits,  be  of  greater  significance  to  the  welfare  of 
an  animal  than  the  absolute  amounts  of  these  substances  which 
the  diet  contains. 

335.  Sherman  and  Pappenheimer's  Observation  on  Rickets. 
Sherman  and  Pappenheimer   (21)   have  recently  described  the 
production  of  rickets  by  a  diet  deficient  in  phosphorus,  and  its 
prevention  by  the  administration  of  a  phosphate.     Their  data 
would  lead  one  to  the  conclusion  that  the  disease  is  brought  about 
by  phosphorus  starvation.    The  isolated  observation  of  these 
investigators  is  of  special  interest  in  that  it  is  explainable  on 
a  very   different  basis   from  that  which   they   had   in  mind. 
Sherman  and  Pappenheimer  fed  groups  of  young  rats  on  the 
following  diets,  and  with  the  results  noted: 

Wheat  flour,  sodium  chlorid,  2%.  No  rickets. 

Wheat  flour,  sodium  chlorid,  2%,  Ca  Lactate,  3%.  Rickets. 

Wheat  flour,  sodium  chlorid,  2%,  Ca  Lactate,  3%,  K2HP04, 0.4%.    No  rickets. 

Instead  of  lack  of  phosphorus,  per  se,  being  the  cause  of  the 
rickets  in  their  animals,  McCollum,  Simmonds,  Shipley  and  Park 
(20)  regard  the  cause  as  due  to  an  unfavorable  ratio  between  the 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    311 

calcium  and  phosphorus,  in  the  absence  of  sufficient  of  the  or- 
ganic factor  which  plays  a  role  in  the  production  of  this  syn- 
drome. The  reasoning  on  which  this  conclusion  rests  was  based 
upon  experimental  data  which  is  of  great  interest  in  illustrating 
one  of  the  several  dietary  situations  which  may  give  rise  to 
rickets  or  similar  conditions.  The  results  of  feeding  the  follow- 
ing diets  will  illustrate  this  principle. 

RATION  3127  RATION  3133 

Rolled   oats    40.0      Rolled   oats    40.0 

Gelatin   10.0      Gelatin    10.0 

Wheat  gluten   7.0      Wheat  gluten 7.0 

NaCl   1.0      NaCl   1.0 

KC1    1.0      KC1    1.0 

CaCOs    2.0      CaC03    2.0 

Dextrin    39.0      Dextrin    38.5 

Butter  fat   .  ....     0.5 


Ration  3127  was  markedly  deficient  in  phosphorus  and  in  fat- 
soluble  A  (anti-xerophthalmic  substance),  but  was  otherwise 
well  constituted.  Its  proteins  were  of  good  quality,  and  its 
content  of  calcium  not  far  from  the  optimum.  Young  rats  fail 
to  grow  on  this  food,  and  develop  severe  ophthalmia.  They  can- 
not live  many  weeks  on  this  diet  because  of  the  severity  of  the 
ophthalmia  which  develops. 

Ration  3133  is  essentially  like  Ration  3127,  but  contains  0.5 
per  cent  of  butter  fat,  which  was  added  to  defer  the  onset  of 
ophthalmia  and  prolong  the  lives  of  the  animals.  This  amount 
of  butter  fat  did  not  suffice  to  protect  against  ophthalmia,  but 
delayed  its  advent  and  diminished  its  rate  of  progress,  and 
therefore  increased  the  life  and  made  possible,  presumably,  a 
greater  amount  of  growth  in  the  skeleton  than  was  possible  on 
diet  3127. 

Both  of  the  rations  just  described,  in  which  the  calcium  con- 
tent was  optimal  and  the  phosphorus  and  fat-soluble  A  very 
low,  produced  in  young  rats  a  pathological  condition  essentially 
identical  with  that  found  in  human  subjects  of  rickets.  The 
lesions  were  more  severe  in  animals  fed  Ration  3133  because  of 
the  small  addition  of  butter  fat,  which  functioned  as  described 
above. 

336.  Excessive  Calcium  Content  in  the  Diet  May  Play  a 
Role  in  Bone  Pathology. — The  following  diet  produces  the 
most  extreme  degree  of  rickets: 


312      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

RATION  3143 

Wheat  (entire  kernel)    33.0 

Maize  (entire  kernel)   33.0 

Gelatin    , .  15.0 

Wheat  gluten   15.0 

NaCl    1.0 

CaCOa    3.0 

The  dietary  faults  in  this  mixture  are  of  a  threefold  nature. 
It  contains  about  twice  the  optimum  amount  of  calcium,  and  is 
very  deficient  in  phosphorus  and  in  fat-soluble  A.  The  calcium: 
phosphorus  ratio  differs  markedly,  therefore,  in  this  diet  from 
that  of  the  other  diets  described  (3127  and  3133).  The  severity 
of  the  lesions  produced  were  much  greater  than  are  ever  seen  in 
human  cases  of  the  disease.  A  small  amount  of  fat-soluble  A 
was  furnished  by  the  wheat  and  maize. 

The  results  of  feeding  young  animals  on  these  diets  in  which 
there  were  faulty  proportions  between  the  calcium  and  phos- 
phorus and  a  deficiency  of  fat-soluble  A,  are  seen  to  depend 
in  their  severity  upon  the  deviation  from  the  optimal  of  the 
Ca:P  ratio.  We  have  repeatedly  observed  that  the  addition  of 
excessive  amounts  of  calcium  carbonate  to  diets  which  were 
deficient  in  phosphorus  and  in  fat-soluble  A,  induce  most  pro- 
nounced disturbances  in  the  growth  of  the  bones.  It  appears 
from  these  studies,  that  it  is  of  more  importance  to  the  indi- 
vidual to  maintain  the  proper  ratio  between  the  calcium  and 
phosphorus  than  to  deviate  from  the  optimal  concentrations  of 
these  two  elements,  when  the  ratios  are  more  favorable. 

337.  Discussion  of  Sherman  and  Pappenheimer's  Experi- 
ments.— In  the  light  of  these  experiments  it  is  possible  to  under- 
stand the  results  of  Sherman  and  Pappenheimer,  and  it  is  neces- 
sary to  place  upon  them  a  different  interpretation  from  that  of 
these  investigators.  This  matter  is  so  important,  not  only  from 
the  standpoint  of  the  etiology  of  rickets,  but  as  an  illustration 
of  the  necessity  of  very  elaborately  planned  series  of  experi- 
ments in  order  that  error  may  be  avoided,  that  a  short  discus- 
sion of  them  will  be  of  value. 

Patent  flour  is  one  of  the  most  deficient  foods  which  enters  into 
the  human  diet,  being  exceeded  in  this  respect  only  by  isolated 
foods  such  as  starch,  sugars,  fats  or  polished  rice.  Bolted  flour 
is  rather  poor  in  protein  and  this  is  of  rather  poor  quality.  It 
is  very  deficient  in  calcium,  phosphorus,  sodium,  chlorin,  iron 
and  possibly  also  in  potassium.  The  only  essential  inorganic 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    313 

element  which  it  probably  contains  in  amount  sufficient  to  meet 
the  needs  of  an  animal  is  magnesium.  Bolted  flour  is  also  very 
deficient  in  the  anti-neuritic  substance  (water-soluble  B)  as 
shown  by  the  frequent  occurrence  of  beri-beri  among  the  people 
of  Labrador  and  Newfoundland,  where  bread  from  this  source 
is  a  principal  article  of  food.  It  is  exceedingly  poor  in  fat- 
soluble  A,  and  in  the  organic  factor  playing  a  role  in  the  preven- 
tion of  rickets.  From  the  standpoint  of  human  nutrition  it  is 
important  also  that  it  lacks  entirely  the  anti-scorbutic  substance. 
The  basal  ration  employed  by  Sherman  and  Pappenheimer  was 
deficient  in  all  the  factors  enumerated  above.  In  the  presence 
of  so  considerable  a  number  of  defects  in  the  ration  it  was  ob- 
viously impossible  to  be  certain  which  were  operative  in  the 
production  of  the  disease.  In  the  light  of  their  experience,  Mc- 
Collum,  Simmonds,  Shipley  and  Park  interpret  the  data  of  Sher- 
man and  Pappenheimer  as  follows  (20). 

When  calcium  was  added  to  the  basal  ration  a  marked  dis- 
proportion in  the  calcium-phosphate  ratio  was  produced,  the 
calcium  being  nearly  optimal  and  the  phosphorus  very  low.  Fat- 
soluble  A  (an  anti-rachitic  substance)  was  almost  lacking,  and 
the  conditions  were  such  under  which  we  should  expect  severe 
rickets  to  develop.  When  neither  calcium  nor  phosphorus  were 
added,  the  content  of  both  these  elements  in  the  diet  was  that 
contained  in  bolted  wheat  flour,  and  the  ratio  was  more  nearly 
the  optimum  than  after  the  calcium  addition,  and,  accordingly, 
osteoporosis  and  not  rickets  should  have  developed.  They  did 
not  state  whether  osteoporosis  existed.  The  animals  were  sorely 
in  need  of  calcium,  yet  its  addition  under  these  peculiar  condi- 
tions caused  the  development  of  the  syndrome  of  rickets  which 
they  would  otherwise  have  escaped.  The  situation  is  analogous 
to  the  effect  of  adding  0.5  per  cent  of  butter  fat  to  diet  3133. 
The  animals  needed  the  fat-soluble  A  which  it  contained,  but 
its  addition  under  the  peculiar  conditions  of  composition  of  that 
diet  increased  the  severity  of  the  rickets  which  developed.  This 
principle  has  not  hitherto  been  conceived  of  by  nutrition  in- 
vestigators, but  it  is  one  of  fundamental  importance.  When 
the  potassium  phosphate  in  the  experiments  of  Sherman  and 
Pappenheimer,  was  added,  the  Ca:P  ratio  was  again  made  more 
favorable  and  rickets  was  prevented.  In  this  case,  the  diet  was 
made  to  contain  fairly  satisfactory  concentrations  of  both  these 
elements,  which  tended  to  promote  normal  bone  development. 

338.     Ratios  Between  Calcium  and  Phosphorus  More  Im- 


314      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

portant  Than  Their  Absolute  Amounts. — Apparently  in  the  rat 
the  profound  disturbances  in  the  deposition  of  lime  salts  in 
cartilages  and  bone  and  the  changes  in  the  cells  of  those  tissues 
which  give  rise  to  the  pathological  complex  known  as  rickets, 
may  be  produced  by  disturbances  in  the  diet  of  the  optimal 
ratio  within  certain  limits  between  calcium  and  phosphorus,  in 
the  absence  of  a  sufficient  amount  of  the  organic  substance  con- 
tained in  cod  liver  oil  to  prevent  them.  It  would  seem  from  the 
results  of  a  large  number  of  experiments  now  available,  that  the 
physiological  relation  in  the  diet  within  certain  limits  between 
the  two  elements  is  of  much  greater  importance  in  insuring  nor- 
mal calcification,  than  the  absolute  amount  of  the  salts  them- 
selves (20). 

339.  Protective  Action  of  the  Organic  Factor  Concerned  in 
the  Causation  of  Rickets. — The  effect  of  the  administration  of 
the  organic  factor  which  has  several  times  been  mentioned  as 
playing  a  role  in  the  etiology  of  rickets,  is  very  easy  to  demon- 
strate by  properly  planned  experiments.  If  one  places  young 
rats  on  a  diet  which  is  too  rich  in  calcium  and  too  poor  in 
phosphorus  and  in  fat-soluble  A,  they  develop  a  condition  in 
their  bones  which  is  characterized  by  the  absence  of  calcium 
salts  in  the  zone  of  primary  calcification.  The  calcium  is  avail- 
able in  abundance  and  a  certain  amount  of  phosphorus  is  present 
in  the  food,  but  owing  to  the  unfavorable  ratio  and  the  absence 
of  the  organic  substance  in  question  deposition  of  calcium  salts 
is  not  possible.  When  young  rats  are  prepared  by  such  a  diet  so 
as  to  insure  that  there  will  be  a  calcium-free  zone  in  their  bones, 
they  respond  with  calcium  deposition  at  once  when  the  defi- 
cient organic  substance  is  exhibited  in  the  diet.  Two  per  cent 
of  cod  liver  oil  administered  to  such  rats  leads  in  the  course  of 
five  to  ten  days  to  the  appearance  in  sections  cut  longitudinally 
through  the  bones,  of  a  fine  line  of  calcium  phosphate,  which 
represents  the  beginning  of  healing  of  the  lesion.  Butter  fat, 
even  to  the  concentration  of  50  per  cent  of  the  food  mixture, 
fails  under  the  condition  of  this  test,  to  stimulate  calcium  phos- 
phate deposition  as  effectively  as  does  2  per  cent  of  cod  liver 
oil.  With  this  technic  it  is  now  possible  in  a  simple  and  easy 
manner  to  test  the  anti-rachitic  property  of  any  food  substance 
with  respect  to  this  organic  factor.  By  changing  the  composi- 
tion of  the  diet  on  which  the  animals  are  prepared,  so  that 
the  calcium-free  condition  is  determined  by  some  other  factor 
in  the  diet,  e.g.,  calcium  or  phosphorus,  it  is  possible  to  test  the 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    315 

anti-rachitic  effect  of  each  of  the  dietary  factors  which  are  con- 
cerned with  the  etiology  of  rickets.  This  test  is  by  far  the 
most  satisfactory  one  yet  devised  for  the  detection  or  approxi- 
mate estimation  of  any  of  the  vitamins. 

340.  Further  Observations  on  Changing  the  Ratios  Be- 
tween Calcium  and  Phosphorus  in  the  Diet. — The  effect  of 
changing  in  the  direction  opposite  to  that  described  above  (Ra- 
tions 3127,  3133  and  3143)  the  ratio  between  the  calcium  and 
phosphorus  has  been  tested.  A  diet  consisting  of  cereal  grains, 
and  legume  seeds  does  not  induce  any  growth  because  it  is  too 
poor  in  calcium.  It  is  likewise  deficient  in  phosphorus,  but  not 
in  so  marked  a  degree  as  in  calcium.  The  content  of  fat-soluble 
A  is  also  far  below  the  optimum  and  its  proteins  are  not  of  the 
best  quality.  The  diet  in  question  is  No.  2638,  described  by 
Shipley,  Park,  Simmonds  and  McCollum  (20). 

RATION  2638. 

Wheat    30.0 

Maize    30.0 

Polished  rice   10.0 

Rolled  oats   10.0 

Peas    10.0 

Navy  beans   10.0 

If  this  diet  is  supplemented  with  common  salt,  calcium  and 
fat-soluble  A,  it  supports  good  growth  and  fair  fertility.  The 
animals  are  not  normal,  however,  as  is  shown  by  subnormal 
fertility,  high  infant  mortality,  the  short  span  of  life,  and  the 
deterioration  of  families  of  animals  restricted  to  it  through 
several  generations. 

When  young  rats  are  confined  to  this  diet  without  supple- 
menting its  calcium  and  protein  content,  they  cannot  grow,  and 
are  brought  into  a  state  of  nutritional  instability.  They  do  not 
constantly  develop  distinct  rickets,  although  the  bones  are  not 
entirely  normal  and  frequently  suggest  rickets.  The  addition  of 
10  per  cent  of  casein,  a  phosphorized  protein,  enhances  the  food 
both  with  respect  to  phosphorus  and  amino-acids,  yet  when  this 
is  done  severe  rickets-like  changes  promptly  develop  provided  no 
calcium  is  added  to  the  diet.  This  is  interpreted  as  a  demon- 
stration that  addition  of  phosphorus,  but  without  exceeding  a 
concentration  which  is  about  the  optimum  under  conditions 
where  more  calcium  were  available,  may  cause  damage,  when 
it  leads  to  the  establishment  of  an  unfavorable  quantitative  re- 


316      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

lation  between  these  elements.  When  casein  and  a  calcium  salt 
are  added  simultaneously,  the  diet  is  greatly  enhanced  and  the 
bones  tend  toward  the  normal  structure.  They  are,  however, 
somewhat  osteoporotic. 

341.  Rickets  Is  Essentially  a  Disease  of  Dietary  Origin. — 
From  what  has  been  said  of  recent  developments  in  the  study  of 
rickets,  there  can  no  longer  be  any  doubt  that  it  is  a  disease 
which  is  essentially  due  to  nutritional  disturbances,  and  that 
dietetic  errors  play  the  dominant  role  in  its  etiology.     It  is  also 
clear  that  at  least  three  dietary  factors,  calcium,  phosphorus  and 
an  organic  substance  which  is  more  abundant  in  cod  liver  oil 
than  in  any  other  substance  known,  are  especially  important  in 
that  rickets  will  develop  unless  proper  amounts  of  these  be  fur- 
nished to  the  growing  animal.    Other  factors  may  favor  or  in- 
terfere with  the  development  of  the  disease. 

342.  The  Calcium  and  Phosphorus  Content  of  the  Blood 
in  Health  and  in  Rickets. — Rowland  and  Kramer  (22)  have  re- 
cently reported  studies  on  the  composition  of  the  blood  with 
respect  to  phosphorus  in  normal  and  in  rachitic  children  which 
are  of  great  interest  in  this  connection.    Whereas  the  content  of 
calcium  in  the  blood  remains  markedly  constant  in  health  and  in 
most  diseases,  the  phosphorus  may  vary  greatly.    The  blood  of 
children  contains  10-11  mgm.  of  calcium  per  100  c.c.  of  serum. 
It  falls  below  this  level  only  in  tetany,  which  condition  is  appar- 
ently directly  brought  about  by  the  reduction  of  the  calcium 
content  of  the  body  fluids.    The  serum  of  adults  contains  9-10.5 
mgm.  of  calcium  per  100  c.c.     The  red  corpuscles  contain  no 
calcium  (22). 

The  inorganic  phosphorus  content  of  normal  blood  of  chil- 
dren is,  according  to  Rowland  and  Kramer,  about  5.4  mgm.  per 
100  c.c.  of  serum.  The  serum  of  adults  contains  but  2.1  mgm. 
of  inorganic  phosphorus  per  100  c.c.  In  rachitic  children  the 
inorganic  phosphorus  content  of  the  serum  may  fall  as  low  as 
0.8-2.9  mgm.  per  100  c.c.  of  serum.  It  is  remarkable  that  on 
the  administration  of  cod  liver  oil  to  such  children  the  inorganic 
phosphorus  content  of  the  serum  at  once  rises  to  the  normal  or 
above.  It  is  highly  suggestive  that  the  heightened  concentration 
of  phosphorus  in  the  serum  may  be  the  cause  of  the  resumption 
of  deposition  of  calcium  phosphate  in  the  bones  in  rickets.  There 
can  no  longer  be  any  doubt  that  cod  liver  oil  possesses  a  pro- 
nounced therapeutic  value  in  the  treatment  of  rickets,  both  in 
human  and  animal  subjects. 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    317 

343.  Why  is  Rickets  Common  in  Some  Places  and  Rare 
in  Others? — By  this  time  it  will  have  become  apparent  to  the 
reader  why  rickets  is  common  in  those  parts  of  the  world  where 
milled  cereal  products,  tubers  and  muscle  meats  form  the  prin- 
cipal components  of  the  dietary.  Such  a  diet  has  repeatedly 
been  shown  to  be  inadequate  for  the  production  of  satisfactory 
milk  by  a  lactating  mother.  When  we  consider  also  that  the 
manufacture  and  use  of  proprietary  infant  foods,  most  of  which 
contain  large  proportions  of  cereal  products,  has  grown  to  vast 
proportions,  and  that  the  practice  of  introducing  very  early  ce- 
reals into  the  diet  of  infants,  with  a  consequent  displacement 
of  milk,  is  all  but  universal  in  recent  times,  it  is  easy  to  under- 
stand how  rickets  would  be  expected  to  be  common.  In  fact, 
the  successful  feeding  of  a  young  omnivorous  animal  during  in- 
fancy and  adolescence  is  a  very  difficult  matter  with  which  to 
succeed  well.  Young  carnivora  in  a  wild  state  eat  glandular 
organs  and  chew  soft  bones  as  soon  as  they  take  their  first  steps 
in  independence  of  the  mother's  milk,  and  under  these  condi- 
tions do  not  develop  skeletal  abnormalities.  When  kept  in  con- 
finement and  fed  upon  muscle  meat,  body  fat,  and  a  bone  so 
large  and  hard  that  little  can  be  gnawed  from  it,  they  invariably 
develop  rickets  (23).  Young  carnivora  are  now  successfully 
reared  in  a  few  places  by  supplying  them  with  liver,  flat  bones 
containing  much  red  marrow,  fat,  and  at  intervals  of  a  few  days 
with  small  birds  or  mammals  which  they  can  entirely  consume. 
Confinement  does  not  seriously  interfere  with  the  development 
of  young  lions  under  such  conditions  of  feeding. 

Young  herbivora,  on  the  other  hand,  begin  very  early  to  eat 
tender  leaves  of  grass,  and  long  before  they  have  been  deprived 
of  their  milk  supply  have  become  consumers  of  large  amounts  of 
forage  plants.  This  type  of  diet  suffices  for  the  normal  devel- 
opment of  the  skeleton. 

It  is  very  different  with  the  human  infant,  and  with  certain 
domestic  animals  which  are  fed  an  omnivorous  type  of  diet. 
The  human  infant  is  nursed  by  a  mother  whose  diet  tends  to 
be  limited  to  the  milled  cereal,  tuber  and  muscle  meat  type 
but  with  just  enough  milk,  cream,  and  green  vegetables  to  pre- 
vent the  development  of  spectacular  breakdown  in  her  nutri- 
tional processes.  Her  milk  is  defective  in  some  degree.  The 
nursing  period  of  the  infant  is  frequently  shortened  for  the  sake 
of  the  interest  of  a  poorly  nourished  mother.  Milk  which  is  fed 
as  a  substitute  for  breast-feeding  is  usually  modified  by  dilu- 


318      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

tion  and  the  addition  of  cereal  water,  or  proprietary  foods  having 
a  cereal  basis.  There  can  be  no  question  that  the  modern 
practice  of  modifying  milks  for  infant  feeding  represents  one  of 
the  most  gigantic  and  tragic  examples  of  persistent  blundering 
of  which  civilized  man  is  guilty.  Fortunately  the  time  seems 
near  at  hand  when  any  manipulations  to  which  cow's  milk  is 
subjected  for  feeding  infants  will  be  carried  out  with  knowledge 
of  what  is  being  done,  and  the  mistake  of  concocting  mixtures 
which  are  entirely  unsuited  for  the  nutrition  of  the  growing 
child  be  avoided. 

344.  Suggestion  of  Cause  of  Occurrence  of  Rickets  in  Dogs 
but  Not  in  Cats. — Young  dogs  which  are  fed  essentially  the  same 
food  that  man  is  now  subsisting  upon  in  Europe  and  America 
are  prone  to  develop  rickets,  whereas  cats,   because   of  their 
tendency  to  prowl  about  in  search  of  birds,  rodents  and  other 
small  creatures,  which  they  destroy  in  large  numbers,  escape  the 
disease.    Their  diet  remains  similar  to  that  of  wild  carnivora, 
because  they  cannot  be  domesticated  sufficiently  to  lead  them 
to  discontinue  the  practice  of  hunting.    The  dog  adapts  himself 
much  more  readily  to  domestication,  and  accepts  his  food  from 
his  master.     In  many  instances  this  does  not  now  prove  satis- 
factory for  the  promotion  of  normal  growth  in  the  skeleton,  and 
rickets  is,  therefore,  of  frequent  occurrence. 

345.  Why  Are  the  Eskimos  and  Lapps  Free  from  Rickets. 
— The  Eskimo,  the  Icelanders  and  the  Lapps  are  free  from  the 
disease,  or  were  until  contact  with  the  world  through  commerce 
changed  the  dietary  habits  of  some  of  them.    The  changes  which 
have   in   certain   instances   brought   about   the   appearance   of 
rickets,  represent  essentially  the  substitution  of  a  considerable 
amount  of  milled  cereal  products,  molasses,  syrup,  legume  seeds 
and  canned  seed  products,  for  a  part  of  their  primitive  kinds  of 
foods.     In  their  primitive  condition  these  were  all  essentially 
carnivorous  in  their  dietary  habits. 

346.  Rickets  Rare  in  Iceland. — Iceland  was  settled  in  the 
ninth  century  by  colonists  from  Ireland  and  from  Scandinavia. 
They  took  with  them  cattle  and  sheep,  and  soon  developed  a 
considerable  animal  industry  which  flourishes  today.     Agricul- 
ture did  not  yield  a  return  for  labor,  and  accordingly  the  people 
of  the  island  subsisted  for  generations  essentially  upon  milk, 
mutton,  fish,  birds'  eggs  at  certain  periods  of  the  year,  and  wild- 
fowl.    Under  such  living  conditions  they  remained  a  vigorous 
people,  but  they  have  suffered  from  deterioration  of  the  teeth 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    319 

during  the  last  seventy-five  years.  It  is  during  this  period  that 
they  have  engaged  most  extensively  in  commerce.  Parallel  with 
the  exportation  of  their  local  products  and  the  importation  of 
cereals  and  other  foods  of  the  type  which  have  come  to  compose 
so  large  a  part  of  the  diet  of  the  urban  population  of  Europe  and 
America  in  recent  decades,  they  have  become  more  and  more 
afflicted  with  dental  caries.  Stefansson  (24)  secured  96  skulls 
from  a  cemetery  in  Iceland  dating  from  the  ninth  to  the  thir- 
teenth centuries,  and  presented  them  to  the  Peabody  museum  of 
Harvard  University.  These  have  been  described  by  Hooton 
(25),  who  found  no  certain  evidence  of  caries  in  any  of  the 
teeth.  Several  teeth  were  broken  but  none  were  decayed.  The 
teeth  of  the  Lapps  are  essentially  perfect  as  are  those  of  the 
Eskimo  in  their  primitive  condition  on  a  carnivorous  diet. 

347.  The  Teeth  in  Rickety  Children. — The  teeth  are  related 
to  the  skeleton  and  their  growth  and  permanence  are  governed 
probably  by  somewhat  similar  laws  of  nutrition  as  are  the  bones. 
It  is  certain  that  in  rickets  the  child  fails  to  develop  sound 
teeth  having  dense  and  faultless  enamel,  and  that  the  roots  of 
the  teeth  do  not  develop  as  they  should.    There  has  been  very 
serious  deterioration  of  the  teeth  of  civilized  people  in  many 
parts  of  the  world  during  the  last  century,  especially  in  parts  of 
England  and  North  America  and  the  British  overseas  dominions. 
This  has  been  variously  attributed  to  the  eating  of  cooked  food, 
soft  food,  failure  to  properly  clean  the  teeth,  etc.    Mouth  hygiene 
has  recently  enjoyed  great  popularity,  and  the  slogan  "a  clean 
tooth  never  decays"  is  frequently  seen,  especially  in  the  adver- 
tisements for  tooth  pastes  and  tooth  brushes.    While  commend- 
able as  a  general  hygienic  measure,  mouth  hygiene  doubtless  has 
little,  if  anything,  to  do  with  the  preservation  of  the  teeth.    All 
measures  hitherto  proposed,  which  stress  cleanliness  and  prompt 
repair,  do  not  get  at  the  root  of  the  evil.    The  development  during 
very  early  life  of  a  sound  set  of  teeth  is  the  most  important  fac- 
tor in  preventive  dentistry.    This  is  not  so  much  dependent  on 
the  softness  or  hardness  of  the  food,  in  infancy  and  very  early 
childhood,  as  it  is  on  the  composition  of  the  diet.    If  this  is  not 
adjusted  in  an  entirely  satisfactory  manner,  the  bones  and  teeth 
will  be  poorly  developed,  and  decay  of  the  teeth  in  early  life  is 
then  unavoidable.    Chewing  hard  foods  is,  however,  an  important 
measure  for  insuring  the  development  of  the  tissues  immediately 
surrounding  the  roots,  and  for  developing  the  jaws. 

348.  Primitive  Man  Had  Neither  Rickets   Nor   Decayed 


320     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Teeth. — In  the  National  Museum  at  Washington  there  are  sev- 
eral hundreds  of  skulls  of  Indians  who  lived  between  two  hun- 
dred and  three  hundred  years  ago.  They  are  from  the  Aleutian 
Islands  down  the  Pacific  coast  through  Honduras  and  Yucatan, 
into  Peru  and  across  to  the  South  Sea  Islands.  Only  a  single 
tooth  showed  dental  caries  in  the  entire  collection.  Among 
these  primitive  peoples  the  diet  was  excellent  from  the 
standpoint  of  chemical  completeness,  and  bone  defects  and  bad 
teeth  were  unknown  or  nearly  so.  The  introduction  of  large 
amounts  of  cereals  and  of  tubers  into  the  diet  by  civilized  and 
urban  populations  has  resulted  during  the  last  century  in  rapid 
falling  off  in  physical  stamina  and  increase  in  skeletal  defects. 

349.  Prevalence  of  Decayed  Teeth  Among  American  Chil- 
dren.— Butler    (26)    points  out  that   an  examination  of  7,059 
children  in  West  Virginia  revealed  16,151  cavities  exclusive  of 
those  containing  fillings.     Under-developed  jaws  and  irregular 
teeth   were   surprisingly   prevalent.      5,935    children   examined 
showed  these  defects  in  1,759  cases.    There  is  nothing  in  our 
national  life  which  is  more  pressing  for  attention  or  more  im- 
portant from  the  standpoint  of  public  health  than  attention  to 
this  matter.    The  only  effective  way  to  attack  the  problem  is 
through  the  diet  of  the  expectant  mother  and  of  the  infant  and 
young   child.     This  must  be  constituted   better  than  is  now 
the  case. 

350.  Significance  of  the  Absence  of  Rickets  in  the  West  of 
Ireland. — Of  more  than  ordinary  interest  in  connection  with 
the  problem  of  the  cause  of  rickets  is  the  immunity  of  the  in- 
habitants of  the  West  of  Ireland   (27)    and  of  the  Island  of 
Lewis  in  the  Hebrides  (28).    In  the  former  place  much  land  is 
unsuitable  for  agriculture  and  cattle  and  sheep  raising  are  highly 
important  industries.    In  fact  there  are  few  places  in  the  world 
where  the  number  of  cattle  in  proportion  to  the  population  is 
greater  than  in  Ireland.    So  far  as  the  author's  investigations 
have  gone,  everything  points  to  the  conclusion  that  wherever  a 
region  is  hilly  and  unfit  for  agriculture,  or  where  the  soil  is  thin 
or  poor  and  suited  only  for  the  grazing  animals,  fine  physical 
development  is  characteristic  of  the  people,  and  rickets  is  un- 
known or  rare  among  the  children.     Where  agriculture  thrives 
and  the  growing  of  cereal  grains  and  tubers  is  the  most  profitable 
form  of  agriculture,  physical  deterioration  as  shown  by  stunted 
growth,    physical    inferiority    and   defective    development    and 
caries  of  the  teeth  are  likely  to  characterize  the  people  both  of 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    321 

the  rural  districts  and  of  the  cities,  but  especially  the  latter, 
because  their  diet  is  likely  to  be  derived  in  larger  proportion 
from  cereal  grains,  tubers  and  muscle  meats. 

351.  Significance  of  the  Conditions  in  the  Island  of  Lewis 
in  Interpreting  the  Cause  of  Rickets. — The  Island  of  Lewis  in 
the  Hebrides  is  of  very  great  interest  in  illustrating  the  greater 
importance  of  nutrition  than  of  hygienic  factors,  in  promoting 
health,  in  reducing  the  infant  mortality  and  in  preventing  skele- 
tal defects.  It  has  already  been  pointed  out  that  the  natives  of 
this  island  subsist  on  a  diet  consisting  in  great  measure  of  cod's 
heads  stuffed  with  cod  livers,  milk,  fish,  turnips,  oat  meal  and 
potatoes,  and  that  their  diet  is  in  great  measure  a  carnivorous 
one,  supplemented  with  small  additions  of  cereal,  tuber  and  root 
vegetables.  They  live  under  the  worst  conceivable  hygienic 
conditions,  with  a  filthy  byre  in  one  end  of  the  dwelling,  with 
no  window  or  only  a  fixed  one  and  with  a  peat  fire  constantly 
burning,  the  smoke  of  which  can  escape  only  through  the 
thatched  roof  and  through  the  open  door.  The  babies  are  taken 
out  of  doors  only  for  a  few  minutes  at  a  time  in  bright  weather, 
are  deprived  of  sunlight  and  breathe  an  atmosphere  sufficiently 
smoky  to  make  inflamed  eyes  the  rule,  yet  they  remain  prac- 
tically free  from  rickets.  The  death  rate  of  infants  in  the 
island  has  not  infrequently  fallen  as  low  as  any  place  in  the 
British  Isles.  The  influence  which  counteracts  the  bad  hygienic 
conditions  is  the  universal  practice  of  breast-feeding,  and  by 
mothers  whose  diet,  although  unattractive  to  the  palate  of  the 
average  European  or  American,  is,  when  evaluated  on  the  basis 
of  its  biological  value  as  shown  by  experiment,  a  highly  satis- 
factory one.  Such  illustrations  as  the  foregoing  are  very  con- 
vincing evidence  that  the  diet  is  the  factor  of  primary  impor- 
tance in  the  etiology  of  rickets,  and  this  belief  is  fully  estab- 
lished by  the  experimental  production  of  rickets  and  related 
skeletal  defects  in  animals,  when  the  diet  was  the  sole  cause  to 
which  the  abnormalities  of  the  bones  could  be  attributed. 

Several  observers  have  recently  reported  the  successful  treat- 
ment of  rickets  by  radiation  with  the  rays  from  a  mercury  vapor 
lamp  (very  short  rays),  and  with  sunlight  (29).  It  is  necessary, 
therefore,  that  any  discussion  of  the  etiology  of  rickets,  to  be 
convincing,  must  satisfactorily  account  for  the  tendency  for 
rickets  to  heal  under  such  treatment.  We  have  now  an  observa- 
tion of  extraordinary  interest  which  is  suggestive  of  the  nature 
of  the  "cure"  which  is  effected  by  light  treatment.  Further 


322     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

studies  will  be  necessary  before  a  conclusive  statement  can  be 
made  relative  to  this  matter,  but  the  observation  in  question 
helps  to  clarify  our  views  on  this  seemingly  conflicting  evidence 
concerning  the  importance  of  light  as  a  means  of  preventing 
rickets. 

352.  A  Method  for  Demonstrating  the  Anti-rachitic  Effect 
of  Cod  Liver  Oil. — It  has  already  been  described  how,  by  ap- 
propriately planned  diets  it  is  possible  to  prepare  young  rats 
so  that  there  is  no  calcium  phosphate  deposited  in  the  zone  of 
primary  calcification  of  the  bones,  and  that  when  this  is  brought 
about  by  deficiency  of  phosphorus,  of  fat-soluble  A  and  anti- 
rachitic  substance,  together  with  a  moderate  excess  over  the 
optimal  of  calcium  in  the  diet,  the  administration  of  cod  liver 
oil  during  a  period  of  a  few  days  leads  to  the  deposition  of  a 
fine  line  of  calcium  salts  across  the  uncalcified  region  in  the 
epiphysis  of  the  bone.    This  sudden  calcification  is  due  to  the 
effect  of  the  organic  nutritive  substance  which  is  abundant  in 
cod  liver  oil,  but  essentially  lacking  in  many  of  our  common 
foods.     It  was  reasoned  by  Shipley,  Park,  Simmonds  and  Mc- 
Collum  (30),  that  if  by  some  means  a  disintegration  of  body 
protoplasm  could  be  suddenly  brought  about,  this  might  result 
in  the  liberation  into  the  body  fluids,  from  the  destroyed  proto- 
plasm, the  organic  factors,  calcium  and  phosphorus,  and  might 
make  possible  a  deposition  of  calcium  phosphate  such  as  is  seen 
in  healing  rickets.     It  seemed  probable  that  a  period  of  fasting 
would  bring  about  a  sufficient  demand  upon  the  body  structures 
to  bring  about  this  result.    A  trial  showed  that  this  result  is 
obtained. 

353.  A  Period  of  Fasting  May  Initiate  the  Healing  of  the 
Lesion  of  Rickets. — When  a  young  rat  is  placed  for  thirty  days 
or  thereabouts  upon  a  diet  such  as  has  been  described  above  for 
the  purpose  of  preparing  it  for  a  demonstration  of  the  thera- 
peutic value  of  cod  liver  oil  in  the  treatment  of  rickets,  and  is 
by  such  a  dietary  regimen  brought  to  a  condition  in  which  the 
zone  of  primary  calcification  is  free  from  lime  salts,  it  will,  we 
may  suppose,  respond  to  illumination,  with  the  initiation  of 
healing  processes,  as  well  as  to  cod  liver  oil  therapy.    If  now, 
we  permit  such  an  animal  to  fast  for  a  period  of  five  days,  and 
thereby  force  it  to  draw  heavily  upon  certain  tissues  for  food 
for  others  whose  functioning  is  most  essential,  it  has  been  shown 
that  healing  of  the  rachitic  lesion  takes  place  in  essentially 
the  same  manner  as  from  the  administration  of  cod  liver  oil, 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    323 

This  seems  to  suggest  a  possible  explanation  for  the  good  results 
observed  in  the  treatment  of  human  rickets  by  excessive  illumi- 
nation with  sunlight  or  with  highly  penetrating  rays.  It  seems 
probable  that  under  such  stimulating  treatment,  tissue  destruc- 
tion may  be  accelerated,  and  that  the  effect  is  to  liberate  thereby 
the  substances  which  exert  an  anti-rachitic  effect.  Provisionally 
it  seems  warrantable  to  adopt  as  a  working  hypothesis  for  further 
investigation  the  view  that  highly  penetrating  rays  produce 
visible  effects  comparable  to  a  period  of  fasting,  and  give  the 
impression  that  rickets  is  healing,  but  under  circumstances  where 
the  actual  cause  of  the  disease  has  not  been  removed.  This  is 
only  palliative  therapy  unless  the  nutritional  situation  is  at  the 
same  time  improved.  It  may  be,  of  course,  that  the  healing  of 
rickets  following  starvation  is  due  to  the  restoration  of  a  normal 
salt  balance  in  the  body  in  which  anabolic  processes  are  brought 
to  a  very  low  level  (48). 

354.  Parallelism  Between  Increase  in  Incidence  of  Rickets 
and  of  Decayed  Teeth. — Since  the  incidence  and  severity  of 
rickets  have  markedly  increased  in  many  places  within  recent 
times,  and  essentially  parallel  with  it  there  has  been  a  marked 
deterioration  of  the  teeth,  associated  with  underdevelopment  of 
the  jaws,  and  an  increased  tendency  to  general  physical  in- 
feriority, we  must  look  to  some  change  or  changes  in  living  con- 
ditions which  have  brought  about  these  results.  On  investigation 
we  find  that  the  pastoral  peoples  of  Asia,  Arabia,  Northern 
Africa  and  Abyssinia  are  essentially  free  from  the  disease.  This 
would  be  attributed  by  many  to  the  "natural"  conditions  of  liv- 
ing. England  and  Scotland  have  a  high  incidence  of  the  disease, 
yet  localities  are  found  in  both  countries  where  the  condition  is 
rare  or  unknown.  Ireland,  the  climate  of  which  differs  but  in- 
significantly from  certain  other  places  where  rickets  is  common, 
contains  districts  where  it  is  unknown.  The  dampness  of  west- 
ern Ireland  is  so  great  as  to  interfere  seriously  with  the  curing 
of  forage  crops  for  hay,  yet  the  lack  of  sunlight  does  not  promote 
rickets  in  the  children,  nor  does  the  "black  house"  of  the  Hebri- 
des, an  extreme  condition  of  lack  of  illumination  and  ventilation, 
cause  the  disease.  It  can  be  produced  in  animals  under  condi- 
tions in  which  all  factors  other  than  diet  are  eliminated,  and  in 
an  animal,  the  rat,  which  is  nocturnal  in  habits,  and  ordinarily 
lives  under  conditions  of  extreme  filthiness,  darkness  and  bad 
air  without  showing  the  least  deviation  from  the  normal  in  the 
structure  of  its  bones.  We  must  look,  therefore,  to  our  methods 


324     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

of  feeding  pregnant  mothers,  lactating  mothers,  and  infants  and 
children,  if  we  are  to  accomplish  our  purpose  of  eradicating  this 
disease  which  stands  first  in  importance  in  causing  physical  in- 
feriority of  the  human  race  in  Europe  and  America.  We  have 
in  rickets  another  incrimination  of  the  milled  cereal,  tuber  and 
muscle  meat  type  of  diet.  The  progress  in  specialization  in  the 
direction  of  limiting  the  food  supply  largely  to  these  classes  of 
articles,  is  synchronous  with  the  increase  in  the  occurrence  of 
rickets.  Wrong  dietary  habits  are  the  cause  of  rickets,  and  also 
of  faulty  tooth  development,  and  of  vulnerability  of  the  teeth, 
which  now  is  causing  so  much  alarm. 

355.  Effect  of  Light  on  Rickets. — Several  observers  have 
recently  reported  the  successful  treatment  of  rickets  in  children 
by  radiation  with  ultra-violet  rays  derived  from  the  mercury 
vapor  lamp,  with  X-rays  and  also  with  sunlight.  It  is  necessary, 
therefore,  that  any  discussion  of  the  etiology  of  rickets,  to  be 
convincing,  must  satisfactorily  account  for  the  tendency  for 
rickets  to  heal  under  such  treatment.  The  work  of  several  ob- 
servers should  be  noted  in  this  connection. 

In  1904  Buchholz  (31)  reported  the  recovery  of  sixteen  chil- 
dren suffering  from  rickets,  on  treatment  with  the  rays  of  the 
"Gluhlicht."  The  nature  of  the  light  was  not  described.  As 
early  as  1890  Palm  (32)  became  convinced  as  the  result  of  a 
noteworthy  topographical  study  of  the  incidence  of  rickets,  that 
the  disease  was  rare  or  absent  from  regions  receiving  much  sun- 
light, and  progressively  more  common  in  others  where  the  amount 
of  sunlight  was  less  abundant.  He  pointed  out  the  desirability 
of  accurate  observations  on  the  chemical  activity  of  the  sun- 
light of  large  cities,  and  recommended  the  use  of  sun  baths  and 
the  removal  of  children  suffering  from  rickets  as  early  as  pos- 
sible to  localities  where  sunshine  abounds.  In  1912  Raczynski 
(33)  again  correlated  the  relationship  which  exists  between  the 
incidence  of  rickets  and  lack  of  sunlight.  He  pointed  out  that 
the  curve  representing  the  number  of  cases  admitted  to  the 
hospital  began  to  rise  sharply  in  January,  reached  a  maximum 
in  May  and  fell  rapidly  in  June. 

Raczynski  reported  an  experiment  with  two  puppies  born  of 
the  same  mother  in  May.  One  was  kept  in  the  sunlight  from 
morning  to  evening,  while  the  other  was  kept  in  total  darkness. 
Both  puppies  were  nursed  exclusively  by  the  mother.  At  the 
end  of  six  weeks  the  two  were  killed  for  examination.  It  was 
found  that  the  one  which  had  lived  in  the  light  was  normal 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    325 

whereas  the  one  kept  in  darkness  had  but  poorly  assimilated 
mineral  salts  necessary  for  the  formation  of  a  skeleton. 

The  use  of  the  X-ray  in  tracing  the  development  of  the  heal- 
ing process  in  rickets  in  children  has  made  possible  more  definite 
and  accurate  observations  on  the  effect  of  therapeutic  agents 
in  the  treatment  of  the  disease.  Fraenkel  and  Lorey  (34)  in 
1910  published  an  atlas  devoted  to  rickets,  in  which  they  re- 
produced X-ray  pictures  of  the  bones  of  rachitic  children  in  all 
stages  of  healing  and  relapse.  Phemister  (35) ,  in  America,  has 
used  this  method  for  the  study  of  the  effects  of  phosphorus  on 
growth  and  ossification.  With  this  aid  Huldschinsky  (36) 
studied  many  cases  of  rickets  in  children  as  they  were  effected  by 
the  ultra-violet  ray.  He  found  that  under  the  influence  of  this 
type  of  radiation  there  was  a  deposition  of  calcium  salts  in  the 
ends  of  the  long  bones  which  was  observable  in  radiographs. 
Control  children  who  were  not  treated  with  the  rays  showed 
no  improvement. 

In  1919  Winkler  (37)  reported  very  spectacular  results  in  the 
treatment  of  rickets  with  the  X-ray.  Putzig  (37)  in  the  same 
year  corroborated  the  findings  of  Huldschinsky  as  did  also 
Karger  (38)  and  Riedel  (39) .  In  1921  further  confirmation  of 
the  observations  of  Huldschinsky  have  appeared  in  the  work  of 
Sachs  (40),  Erlacher  (41),  Mengert  (42)  and  Hess  (43).  Hess' 
views  regarding  the  curative  effects  of  radiant  energy  on  children 
suffering  from  rickets,  and  based  on  his  own  observations,  led  him 
to  assert  in  1920  (44)  that  the  violet  ray  was  not  effective  in 
the  treatment  of  rickets.  He  further  stated  in  connection  with 
a  discussion  of  the  value  of  sunlight  as  a  preventive  measure 
against  rickets:  "But  the  fact  that  rickets  is  exceptional  in  the 
Arctic  regions  where  there  is  lack  of  sunlight  for  the  greater  part 
of  the  year  is  a  strong  argument  against  its  predominant  influ- 
ence." Even  Glisson  in  1650  (8)  expressed  the  view  that  moist, 
foggy  climates  were  an  etiological  factor  in  the  production  of 
rickets.  Since  the  appearance  of  the  work  of  the  German  in- 
vestigators noted  above  Hess  (44)  has  reported  new  experiments 
which  are  fully  in  accord  with  the  latter  in  supporting  the  view 
that  ultra-violet  light  and  sunlight  are  very  effective  in  the 
treatment  of  the  disease.  In  1921  Hess  and  Unger  (44)  reported 
their  demonstration  by  means  of  the  X-ray,  that  sunlight  alone 
possesses  the  same  curative  action  as  does  the  ultraviolet  ray 
in  human  rickets.  They  exposed  rachitic  infants  for  periods  of 
one-half  hour  to  several  hours  daily  whenever  sunlight  was 


326      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

available.  Different  parts  of  the  body  were  in  turn  subjected  to 
the  action  of  the  rays.  Under  this  treatment  calcification  of 
the  cartilage-shaft  junctions  of  the  bones  occurred. 

Thus  far  all  investigations  relating  to  the  curative  effects  of 
sunlight  or  of  ultraviolet  rays  in  rickets  had  been  made  on 
human  subjects  and  all  the  evidence  regarding  their  effects  had 
been  furnished  by  radiographs.  Park,  Powers,  Shipley,  Sim- 
monds  and  McCollum  (45)  have  recently  carried  out  experi- 
ments with  rats  which  were  fed  a  diet  which  had  previously 
been  shown  to  induce  rickets  within  a  few  weeks.  Two  groups 
of  animals  were  employed.  These  were  fed  the  same  diet,  and 
one  group  was  kept  in  a  northeast  room  in  which  there  was  no 
direct  illumination  except  through  glass  and  the  light  was  always 
subdued.  The  other  group  was  kept  in  direct  sunlight  in  sum- 
mer for  varying  periods.  Individuals  were  given  the  sun  treat- 
ment for  62-67  days,  and  the  average  period  of  exposure  was 
four  hours  daily. 

The  control  animals  which  were  kept  in  a  room  with  little 
light,  all  developed  severe  rickets  as  shown  by  autopsy  and 
histological  examination  of  the  bones.  They  also  showed  the 
typical  deformities  described  earlier  in  this  chapter.  The  illumi- 
nated animals  on  the  other  hand,  while  they  did  not  grow  in  a 
satisfactory  manner,  did  increase  in  weight  to  a  certain  extent, 
and  none  showed  any  signs  of  rickets.  This  was  confirmed  by 
careful  autopsies  and  by  histological  examination  of  sections  of 
the  bones. 

The  diet  employed  in  this  experiment  consisted  of  wheat  33 
per  cent,  maize  33  per  cent,  gelatin  15  per  cent,  wheat  gluten 
15  per  cent,  sodium  chlorid  1.0  per  cent  and  calcium  carbonate 
3.0  per  cent.  The  diet  was  of  good  quality  in  respect  to  the 
content  and  quality  of  its  protein.  It  contained  about  twice  the 
optimal  content  of  calcium;  less  than  the  optimal  content  of 
phosphorus  and  was  very  poor  in  fat-soluble  A.  Any  diet  so 
constituted  will,  as  we  have  previously  shown,  cause  the  develop- 
ment of  a  condition  of  the  bones  which  is  anatomically  indis- 
tinguishable from  that  seen  in  rickets  of  human  beings. 

The  marked  improvement  in  the  rats  exposed  to  sunlight  over 
those  which  were  not,  affords  convincing  evidence  that  the  good 
effect  of  the  illumination  was  not  limited  to  the  bones,  but  had 
a  profound  influence  on  all  the  cells  of  the  body.  Sunlight  is  in 
this  respect  comparable  with  cod  liver  oil,  which,  when  added 
to  the  diet  employed  in  these  experiments,  not  only  makes  the 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    327 

bones  essentially  normal  in  structure,  but  also  makes  the  appear- 
ance of  the  animals  receiving  it  greatly  superior  to  control  ani- 
mals on  the  same  diet  without  the  oil. 

These  results  have  a  wide  biological  significance.  Cod  liver 
oil  contains  and  sunlight  embodies  something  which  is  essential 
for  optimal  cellular  functioning.  Either  cod  liver  oil  or  light, 
when  made  available  to  an  animal  previously  deprived  of  either, 
enables  the  organism  to  put  into  operation  defense  mechanisms 
or  adaptations  which  it  could  otherwise  not  avail  itself  of. 
Neither  cod  liver  oil  nor  light  corrects  the  defects  of  the  diet 
as  respects  the  faulty  relation  of  calcium  and  phosphorus,  for 
the  oil  does  not  contain  either  of  these  elements.  It  is  this  faulty 
content  of  the  diet  with  respect  to  calcium  and  to  phosphorus 
which  plays  the  most  significant  role  in  predisposing  the  animal 
to  the  development  of  the  rachitic  syndrome.  Either  cod  liver 
oil  or  light  serves,  however,  to  make  the  cells  function  more  satis- 
factorily under  these  unfavorable  conditions  than  they  otherwise 
could  do.  They  raise  the  potential  of  cellular  activity  so  as  to 
secure  a  most  efficient  utilization  of  the  calcium  and  phosphorus 
available  for  bone  formation.  Without  one  or  the  other  of  these 
agencies  acting,  the  animals  would  develop  rickets  on  this  diet, 
but  under  their  influence  bone  growth  is  essentially  normal. 
Under  their  influence  the  animals  do  not  suffer  from  general 
physical  debility  as  they  otherwise  would.  Sunlight  enabled  the 
animals  to  adapt  themselves  not  only  to  a  shortage  of  a  vitamin 
(fat-soluble  A)  but  also  to  the  unfavorable  relationship  between 
the  calcium  and  phosphorus  in  the  diet. 

It  is  apparent  from  these  results  that,  within  certain  limits, 
diets  which  are  deficient  in  some  degree  with  respect  to  certain 
factors,  when  the  body  receives  only  subdued  light  or  is  kept  in 
darkness,  may  suffice  in  much  greater  degree  to  maintain  nutri- 
tion and  promote  well-being  in  the  same  species  under  circum- 
stances where  a  good  supply  of  sunlight  is  available.  It  seems 
to  be  definitely  proven  that  a  certain  amount  of  sunlight  is 
beneficial  to  physiological  well-being.  The  possibility  is  also 
suggested  that  a  diet  which  supplies  the  optimal  amounts  of  cer- 
tain dietary  factors  for  an  animal  living  in  darkness  or  semi- 
darkness,  may  furnish  excessive  amounts  for  an  individual  which 
is  bathed  in  light.  This  question  is  deserving  of  further  inquiry. 

Since  cod  liver  oil  is  able  to  act  as  a  substitute  for  active 
light  in  its  effect  on  certain  of  the  processes  of  growth  and  metab- 
olism, it  becomes  necessary  to  think  of  it  (and  probably  certain 


328     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

other  foods  as  well)  as  being  able  to  compensate  for  deprivation 
of  light.  The  mechanism  which  is  operative  between  light  and 
certain  foods  is  reciprocal,  in  that  they  are  interchangeable.  It 
is  conceivable  that  the  extent  to  which  the  body  is  irradiated 
by  sunlight  may  determine  in  an  important  degree  the  amounts 
of  certain  dietary  essentials  which  will  suffice  for  the  mainte- 
nance of  satisfactory  physiological  well-being. 

It  may  well  be  significant  that  people  who  live  in  the  far 
north  and  receive  little  sunlight,  take  regularly  in  their  food 
large  amounts  of  fish  oils  and  other  fats.  The  same  is  true  of 
Arctic  animals  of  carnivorous  dietary  habits.  This  element  in 
their  food  must,  it  appears,  compensate  for  the  lack  of  illumina- 
tion, for  rickets  is  very  rare  in  that  part  of  the  world.  On  the 
other  hand,  rickets  is  also  rare  in  the  warmer  parts  of  the 
world,  and  this  may  now  in  great  measure  be  correlated  with  the 
amount  of  sunlight  which  is  received.  We  may  expect  severe 
rickets  to  become  common  in  the  Arctic  regions  should  the  type 
of  diet  which  is  common  in  lower  latitudes  of  America  supplant 
the  primitive  diet.  There  appears,  as  already  mentioned  earlier 
in  this  chapter,  to  be  evidence  that  rickets  is  already  appearing 
among  children  in  northern  Alaska.  The  infants  in  the  "black 
house"  of  the  Hebrides  are  protected  against  skeletal  defects 
through  the  consumption  by  their  mothers  of  cod  heads  stuffed 
with  minced  cod  livers. 

It  appears,  therefore,  that  Nature  has  provided  a  substitute 
for  light  in  an  organic  substance  or  substances  contained  in  cer- 
tain foods,  and  that  the  function  of  these  may  be  in  some  way 
associated  with  the  provision  of  some  form  of  radiant  energy, 
produced,  it  may  be,  through  oxidation  of  compounds  of  unique 
character.  This  view,  resting  as  it  does,  on  a  sound  experi- 
mental basis,  opens  a  new  and  attractive  field  for  investigation. 
It  introduces  into  nutrition  problems  factors  which  the  physicist 
must  be  called  upon  to  help  solve,  and  must  stimulate  profound 
inquiry  into  the  therapeutic  possibilities  of  purely  physical 
agencies  which  have  hitherto  been  employed  in  a  haphazard 
manner  and  based  on  empirical  reasoning. 

It  should  be  emphasized,  in  view  of  what  has  just  been  said, 
about  the  possibility  of  affording  a  measure  of  protection  for  an 
animal  restricted  to  a  diet  which  is  deficient  in  certain  respects, 
by  providing  it  with  a  liberal  supply  of  a  particular  vitamin 
(calcium-depositing  substance),  that  this  does  not  afford  a 
justification  for  relaxing  our  insistence  upon  the  wisdom  of 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    329 

taking  regularly  a  diet  which  is  just  as  nearly  of  optimal  com- 
position as  possible.  When  the  diet  is  defective  in  any  respect, 
the  enhancement  of  the  food  with  respect  to  any  other  factor  or 
factors  will  make  the  animal  able  to  appear  better  nourished 
than  it  otherwise  would,  but  the  defect  is  certain  to  leave  its 
mark  somewhere  in  the  life  history  of  the  individual  or  its 
progeny. 

BIBLIOGRAPHY 

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330     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

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of  rachitis  and  similar  diseases  in  the  rat  by  deficient  diets,  Jour. 
Biol.  Chem.,  1921,  xlv,  333. 

Shipley,  Park,  McCollum,  Simmonds,  and  Parsons:  Studies  in  ex- 
perimental rickets,  ii.  The  effects  of  cod  liver  oil  administered  to 
rats  with  experimental  rickets,  Ibid.,  343. 

Shipley,  Park,  McCollum,  and  Simmonds:  Studies  on  experimental 
rickets,  iii.  A  pathological  condition  bearing  fundamental  resem- 
blances to  rickets  of  the  human  being  resulting  from  diets  low  in 
phosphorus  and  fat-soluble  A:  The  phosphate  ion  in  its  prevention, 
The  Johns  Hopkins  Hosp.  Bull.,  1921,  xxxii,  160. 

McCollum,  Simmonds,  Shipley,  and  Park:  Studies  on  experimental 
rickets,  iv.  Cod  liver  oil  as  contrasted  with  butter  fat  in  the 
protection  against  the  effects  of  insufficient  calcium  in  the  diet, 
Proc.  of  the  Soc.  for  Exper.  Biol.  and  Med.,  1921,  xviii,  275. 

Shipley,  Park,  McCollum,  and  Simmonds:  Studies  on  experimental 
rickets,  v.  The  production  of  rickets  by  means  of  a  diet  faulty  in 
only  two  respects,  Proc.  of  the  Soc.  for  Exper.  Biol.  and  Med.,  1921, 
xviii,  277. 

McCollum,  Simmonds,  Shipley,  and  Park:  Studies  on  experimental 
rickets,  vi.  The  effects  on  growing  rats  of  diets  deficient  in  calcium, 
Amer.  Jour.  Hyg.,  1921,  I,  492. 

Shipley,  Park,  McCollum,  and  Simmonds:  Studies  on  experimental 
rickets,  vii.  The  relative  effectiveness  of  cod  liver  oil  as  contrasted 
with  butter  fat  for  protecting  the  body  against  insufficient  calcium 


RELATION  OF  DIET  TO  ETIOLOGY  OF  RICKETS    331 

in  the  presence  of  a  normal  phosphorus  supply,  Amer.  Jour,  of  Hyg., 
1921,  1,  512. 

McCollum,  Simmonds,  Shipley,  and  Park:  Studies  on  experimental 
rickets,  viii.  The  production  of  rickets  by  diets  low  in  phosphorus 
and  fat-soluble  A,  Jour.  Biol.  Chem.,  1921,  xlvii,  507. 

21.  Sherman,  H.  C.,  and  Pappenheimer,  A.  M.:     A  dietetic  production  of 

rickets  in  rats  and  its  prevention  by  an  inorganic  salt,  Proc.  Soc. 
for  Exper.  Biol.  and  Med.,  1921,  xviii,  193. 

Hess,  A.  F.,  McCann,  G.  F.,  and  Pappenheimer,  A.  M.:  Experimental 
rickets  in  rats.  ii.  The  failure  of  rats  to  develop  rickets  on  a  diet 
low  in  vitamine  A,  Jour.  Biol.  Chem.,  1921,  xlvii,  395. 

22.  Howland,  J.,  and  Kramer,  B.:     Calcium  and  phosphorus  in  the  serum 

in  relation  to  rickets,  Amer.  Jour.  Dis.  of  Child.,  1921,  xxii,  105. 

23.  Hansemann,    D.:      Ueber    den    Einfluss    der    Domestication    auf    die 

Enstehung  der  Krankheiten,  Berliner  klin.  Wochenschr.  1906,  xliii, 
629,  and  670. 

Smith,  E.:  Archeological  Survey  of  Nubia,  ii,  21,  Cairo.  Cited  by 
Findlay  (2). 

24.  Stefansson,  V.:    Personal  communication. 

25.  Hooton,  E.  A.:     On  certain  Eskamoid  characters  in  Icelandic  skulls, 

Amer.  Jour,  of  Physical  Anthropology,  1918,  1,  53. 

26.  Butler,  H.  B.:     Importance  of  Oral  Hygiene  during  childhood,  Amer. 

Jour,  of  Pub.  Health,  1921,  xi. 

27.  Mackenzie,  W.  L.:     The  Carnegie  United  Kingdom  Trust.    Physical 

welfare  of  mothers  and  children  (of  Scotland),  East  Port,  Dun- 
fermline.  1917. 

28.  Mellanby,  E.:     Accessory  food  factors  (vitamines)  in  the  feeding  of 

infants,  Lancet,  1920,  i,  1290. 

29.  Hess,  A.  F.,  and  linger,  L.:     The  clinical  role  of  fat  soluble  vitamin: 

Its  relation  to  rickets,  Jour.  Amer.  Med.  Assoc.,  1920,  Ixxiv,  217. 
Huldschinsky,  K.:     Treatment  of  tetany  with  ultraviolet  rays,  Ztsch. 

f.  Kinderh.,  1920,  xxvi,  207,  Sept.  13. 
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bestrahlung,  Ztschr.  f.  orthop.  Chir.,  1920,  Ixxxix,  426. 
Hess,   and  linger:      An   interpretation   of  the   seasonal   variation   of 

rickets,  Amer.  Jour,  of  Dis.  of  Child.,  1921,  xxii,  186. 

30.  Shipley,  Park,  McCollum,  and  Simmonds:     Unpublished  data. 

31.  Buchholz,    E.:      Ueber    Lichtbehandlung    der    Rachitis    und    andere 

Kinderkrankheiten,  Verhandlungen  der  Gesellschaft  fur  Kinder- 
heilkunde  in  der  Abteilung  fur  Kinderheilkunde  der  76  Versammlung 
der  Gesellschaft  Deutscher  Naturforscher  und  Aerzte  in  Breslau, 
1904,  xxi,  216. 

32.  Palm,  T.  A.:    The  Geographical  Distribution  and  Etiology  of  Rickets, 

The  Practitioner,  1890,  xlv,  270,  and  321. 

33.  Raczynski,  J.:     Communications  sur  le  rachitisme.   1.    Recherches  ex- 

perimentales  sur  le  manque  d'action  du  soleil  domme  cause  du 
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34.  Fraenkel,  E.,  and  Lorey,  A.:     Archiv  und  Atlas  der  normalen  und 

pathologischen  Anatomic  in  typischen  Rontgenbild,  Hamburg,  Lucas 
Grafe  and  Sillem,  1910. 


332     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

35.  Phemister,  D.  B.:     The  effect  of  phosphorus  on  growing  normal  and 

diseased  bones,  Jour.  Amer.  Med.  Assoc.,  1918,  Ixx,  1737. 

36.  Huldschinsky,  K. :     Heilung  von  Rachitis  durch  Kiinstliche  Hohensonne, 

Deutsch.  med.  Wochenschrift,  1919,  xlv,  712. 

37.  Winkler,  F.:    Ueber  die  Strahlungstherapie  der  Rachitis,  Monatschr.  f. 

Kinderheilk.,  1919,  xv,  520. 

Putzig,  H.:  Die  Behandlung  der  Rachitis  mit  Kiinstlicher  Hohensonne, 
Therap.  Halbmonatschr.,  1920,  viii,  234. 

38.  Karger,  P.:     Zur   Kenntniss   der  zerebralen   Rachitis,    Monatschr.    f. 

Kinderheilk,  1920,  xviii,  21. 

39.  Riedel,    G.:      Die    Erfolge    der    Quartzlichtbestrahlung    bei    Rachitist 

Miinchen.  med.  Wochenschr.,  1920,  Ixvii,  838. 

40.  Sachs,  F.:    Untersuchungen  iiber  den  Einfluss  des  Ultraviolettlichtes 

auf  die  latente  Sauglingstetanie,  Jahrb.  f.  Kinderheilk.,  1921,  xciii,  167. 
Miinchen.  med.  Wochenschrift,  1921,  Ixviii,  985. 

41.  Erlacher,  P.:     Ueber  Heilerfolge  bei  Rachitis  nach  Quattzlichtbestrah- 

lung,  Wiener  klin.  Wochenschr.,  1921,  xxxiv,  241. 

42.  Mengert,    E.:    Ueber    verbeugende    Hohensonnenbestrahlung    gegen 

Rachitis,  Deutsch.  med.  Wochenschrift,  1921,  xlvii,  675. 

43.  Hess,  A.  F.:    The  clinical  role  of  the  fat-soluble  vitamin.    Its  relation 

to  rickets,  Jour.  Amer.  Med.  Assn.,  1920,  Ixxiv,  217. 

44.  Hess,  A.  F.,  and  Unger,  L.  J.:     The  cure  of  infantile  rickets  by  sun- 

light, Jour.  Amer.  Med.  Assn.,  1921,  Ixxvii,  39. 

45.  McCollum,  E.  V.,  Simmonds,  N.,  Shipley,  P.  G.,  and  Park,  E.  A.: 

Studies  on  Experimental  Rickets,  viii.  The  production  of  rickets 
by  diets  low  in  phosphorus  and  fat-soluble  A,  Jour.  Biol.  Chem., 
1921,  xlvii,  507. 

Shipley,  McCollum,  and  Simmonds:  Studies  on  experimental  rickets, 
ix.  Lesions  in  the  bones  of  rats  suffering  from  uncomplicated  beri- 
beri, Jour.  Biol.  Chem.,  1921,  xlix,  399. 

McCollum,  Simmonds,  Shipley,  and  Park:  Studies  on  experimental 
rickets,  xii.  Is  there  a  substance  other  than  fat  soluble  A  associated 
with  certain  fats  which  plays  an  important  role  in  bone  develop- 
ment?, Jour.  Biol.  Chem.,  1922,  xlix,  5. 

McCollum,  Simmonds,  Shipley,  and  Park:  Studies  on  experimental 
rickets,  xv.  The  effect  of  starvation  on  the  healing  of  rickets,  Johns 
Hopkins  Hosp.  Bull.  1922,  xxxiii,  31. 

Powers,  G.  F.,  Park,  E.  A.,  Shipley,  P.  G.,  McCollum,  E.  V.,  and  Sim- 
monds, N.:  Studies  on  experimental  rickets,  xiv.  The  prevention 
of  the  development  of  rickets  in  rats  by  sunlight,  Jour.  Amer.  Med. 
Assn.,  1922,  Ixxviii,  159. 


FIG  16. — Illustrates  the  appearance  of  the  ex- 
terior of  the  thorax  of  a  normal  and  of  a  rachitic 
rat.  The  animals  were  the  same  age.  The  normal 
one  on  the  left  exhibits  the  perfection  of  form  in 
this  species.  The  rickety  rat  was  small,  round 
shouldered,  and  had  the  typical  "pigeon  breast 
seen  in  severe  cases  of  rickets  in  children.  The 
bending  inward  of  the  ribs  resulted  in  a  flattening 
and  deformity  of  the  thorax,  and  the  formation  of 
a  groove  along  the  line  of  insertion  of  the  dia- 
phragm. 


AttacWmi 
of  Diatthr 


FIG.  17. — Illustrates  the  appearance  of  the  inside  of  the  thorax  of  a  normal  rat  and 
also  one  suffering  from  rickets.  Note  the  smooth  and  symmetrical  form  of  the  normal 
animal  on  the  left.  On  the  right  the  rickety  rat  is  seen  to  have  great  deformity  of  the 
thorax.  The  shoulders  are  rounded  and  the  breast  bone  misshapen.  There  are  large 
knobs  on  the  ribs  due  to  spontaneous  fracture  and  attempt  at  healing.  The  junctions  of 
the  ribs  with  the  cartilages  are  enlarged,  and  the  ribs  are  bent  inward  at  their  ventral 
extremity.  The  beaded  condition  of  these  is  the  analogue  of  the  "rachitic  rosary"  seen  in 
children. 


CHAPTER  XV 

THE  NURSING  MOTHER  AS  A  FACTOR  OF  SAFETY 
IN  THE  NUTRITION  OF  THE  SUCKLING 

355.  New-Born  Young  Dependent  on  Milk. — It  is  a  remark- 
able fact  that  for  a  time  after  birth  every  mammal  is  incapable 
of  taking  the  type  of  diet  which  suffices  for  the  maintenance  of 
normal  nutrition  in  the  adult.    It  must  have  milk  for  a  certain 
period.    The  duration  of  dependency  on  a  milk  diet  is  not  the 
same  for  different  species.    Among  all  the  mammals  the  young 
of  the  guinea  pig  appears  to  have  the  shortest  period  of  de- 
pendence upon  the  mother.    It  is  born  in  a  very  advanced  state 
of  maturity  and  can  eat  grass  or  succulent  vegetables  during  the 
first  or  second  day  of  post-natal  life.    The  young  rat  may  safely 
be  weaned  at  the  age  of  twenty-five  days,  provided  the  diet  of 
the  mother  during  the  time  of  nursing  is  satisfactory,  and  pro- 
vided the  young  are  put  as  soon  as  weaned,  upon  a  diet  of  good 
quality.    If  the  mother's  diet  has  been  faulty  in  any  respect  it 
may  be  necessary  to  prolong  the  nursing  period  to  thirty  to 
fifty  days  before  the  young  reach  a  state  of  independence.    The 
young  pig  (swine)  is  able  to  eat  at  six  to  eight  weeks  fairly 
liberally  of  the  normal  diet  of  forage  plants  and  cereals  or 
roots.    The  human  infant  must  live  during  the  first  year  of  life 
largely  on  a  milk  diet,  and  cannot  thrive  without  a  fairly  liberal 
supply  of  milk  during  a  considerable  part  of  the  entire  period 
of  growth.    Even  eggs  cannot  entirely  replace  milk  during  any 
part  of  the  nursing  period.    It  is  of  great  importance  that  we 
should  understand  the  relationship  between  the  character  of  the 
diet  of  the  lactating  female  and  the  quality  of  the  milk  secreted. 
Our  knowledge  of  this  phase  of  nutrition  has  been  greatly  en- 
hanced during  the  last  few  years,  and  the  general  principles  are 
now  well  understood. 

356.  Effect  of  Faulty  Diet  on  the  Capacity  of  the  Lactating 
Female  to  Produce  Normal  Milk. — In  order  to  gain  information 
concerning  the  relation  between  the  character  of  the  diet  of  the 
mother  and  the  nutritive  quality  of  her  milk,  McCollum  and 

333 


334     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Simmonds  (1)  carried  out  a  series  of  experiments  with  lactating 
rats,  whose  diets  were  faulty  in  known  respects.  They  observed 
the  effect  on  the  growth  of  the  young  nursed  by  mothers  receiving 
a  highly  satisfactory  diet  until  the  completion  of  their  term  of 
pregnancy.  As  soon  as  the  young  were  born  the  litters  were  in 
all  cases  reduced  to  four  in  order  that  the  nutritive  undertaking 
of  the  mother  should  be  in  no  case  burdensome.  The  mother 
was  at  once  placed  upon  a  diet  which  would  not  induce  any 
growth  in  a  young  rat  separated  at  weaning  time  from  the 
mother.  The  food  of  the  mothers  in  the  course  of  various  experi- 
ments was  made  faulty  in  different  respects.  The  faults  included 
all  the  recognized  factors  which  contribute  to  making  a  diet 
satisfactory,  but  the  number  of  deficiencies  in  any  single  diet 
varied  from  one  to  three. 

In  one  case  a  mother  was  fed  upon  a  diet  of  purified  protein, 
carbohydrate  and  a  salt  mixture  supplemented  with  an  alcoholic 
extract  of  wheat  germ  to  furnish  the  factor,  water-soluble  B. 
This  diet  contained  everything  necessary  for  the  nutrition  of  a 
young  rat  during  growth,  except  fat-soluble  A.  The  problem 
was  to  find  whether  the  mother  could,  through  the  agency  of  the 
mammary  gland,  synthesize  this  substance  from  some  other 
component  of  her  diet.  Experience  has  shown  that  the  young 
animal  after  weaning  cannot,  for  its  own  preservation,  produce 
the  fat-soluble  A  from  other  complexes  in  its  food.  The  results 
of  these  experiments  indicated  clearly  that  the  quantity  of  fat- 
soluble  A  in  the  milk  of  the  mother  confined  to  this  deficient 
food  was  distinctly  below  the  optimum,  or  below  the  average 
content  of  milks.  The  milk  secreted  under  the  circumstances 
did  not  furnish  a  sufficient  amount  of  this  substance  to  promote 
growth  in  the  young  at  the  maximum  rate. 

357.  Mammary  Gland  Has  No  Power  to  Synthesize  a 
Vitamin. — When  McCollum  and  Davis  first  observed  the  neces- 
sity in  the  diet  for  growth  of  something  which  could  be  furnished 
by  certain  fats  but  not  by  others  or  not  by  non-lipin  components 
of  the  diet,  they  were  impressed  by  the  experiments  reported  by 
Osborne  and  Mendel  (2).  The  latter  appeared  to  have  demon- 
strated that  a  pregnant  female  could  cause  the  development  of 
normal  young,  and  thereafter  secrete  milk  containing  everything 
necessary  for  their  normal  nutrition,  while  herself  confined  to  a 
diet  which  lacked,  so  far  as  could  be  seen,  not  only  the  amino- 
acid  lysin,  but  likewise  any  source  of  the  dietary  factor  now 
designated  as  fat-soluble  A.  The  experimental  diet  consisted 


THE  NUTRITION  OF  THE  SUCKLING  335 

of  gliadin,  protein-free  milk,  starch  and  lard.  Osborne  and 
Mendel's  experiment  in  reproduction  on  this  food  mixture  seemed 
to  prove  that  the  synthesis  of  vitamins  by  the  mammary  gland 
was  possible.  It  appeared,  therefore,  that  they  could  be  pro- 
duced by  the  mother  for  the  preservation  of  the  species,  but  not 
by  the  young  for  their  own  preservation.  This  assumption  was 
at  that  time  believed  to  be  supported  by  satisfactory  experi- 
mental data  (3).  Later  studies  by  McCollum  and  Simmonds 
have  clearly  demonstrated  that  there  can  be  no  adequate  nutri- 
tion of  the  young  while  nursing  a  mother  whose  diet  is  deficient 
in  fat-soluble  A,  or  any  other  substance  which  the  young  rat 
requires  for  its  nutrition  in  after-weaning  periods. 

It  has  been  shown  by  Osborne  and  Mendel  (4)  that  body  fat 
of  beef  cattle  contains  a  small  amount  of  fat-soluble  A.  It 
seems  certain  that  the  body  fats  of  any  animal  fed  for  a  time  a 
diet  rich  in  this  substance  will  serve  as  a  reserve  supply  of  this 
factor,  which  the  mother  can  draw  upon  and  secrete  into  the 
milk.  In  other  experiments  of  McCollum  and  Simmonds  definite 
evidence  was  secured  which  proved  that  fat-soluble  A  is  not 
present  in  the  milk  unless  it  is  furnished  in  the  food  of  the  lac- 
tating  animal.  The  presence  of  some  fat-soluble  A  in  the  tissues 
of  the  mother  makes  it  especially  difficult  to  obtain  milk  entirely 
free  from  this  substance. 

Through  similar  experiments  with  diets  which  contain  fat- 
soluble  A  but  not  water-soluble  B,  evidence  was  also  secured 
that  for  a  time  the  mother  is  able  to  secure  this  dietary  factor 
from  her  reserve  supply,  but  none  of  the  growth  curves  indicated 
that  this  substance  is  present  in  adequate  amounts  in  the  milk 
when  the  diet  of  the  mother  is  lacking  therein.  It  seems  certain 
that  neither  of  these  dietary  essentials  is  present  in  abundance 
in  milk  unless  the  diet  of  the  lactating  animal  serves  as  the 
source. 

358.  Tendency  for  the  Lactating  Mother  to  Sacrifice  Her 
Tissues  to  Maintain  the  Normal  Composition  of  Her  Milk. — 
It  is  hardly  to  be  expected  that  the  quality  of  the  milk  should 
be  maintained  unimpaired  when  the  nutrition  of  the  lactating 
mother  falls  far  below  the  normal  for  any  very  extended  period. 
Indeed,  many  observations  are  recorded  which  show  that  the 
milk  secreted  by  poorly  nourished  women  is  of  low  nutritive 
value.  There  is,  nevertheless,  some  tendency  for  the  mother  to 
sacrifice  herself  in  order  to  produce  milk  for  the  maintenance 
of  her  offspring.  Ducaisne  (5)  observed  that  during  the  siege 


336     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

of  Paris,  young  and  vigorous  women  were  able  to  produce  milk 
enough  to  maintain  their  infants.  In  some  instances  the  lactat- 
ing  mothers,  while  partially  fasting,  actually  increased  their 
weight. 

During  the  great  war  the  state  of  malnutrition  among  the 
children  of  many  parts  of  Europe  caused  great  concern.  Chemi- 
cal investigations  of  the  composition  of  human  milks  produced 
by  women  not  able  to  furnish  proper  nourishment  for  their  babies 
were  reported  by  Momm  and  Kraemer  (6).  They  observed  in 
the  fat  content  no  appreciable  deviation  from  the  normal. 
Kaupe,  a  pediatrist  of  Bonn  (7),  found  in  his  clinic  that  the  milk 
secreted  by  women  during  the  war  was  sufficient  in  amount  to 
induce  during  the  first  few  weeks  of  life  satisfactory  nutrition. 
The  children  did  not,  however,  gain  in  weight  as  they  should. 
The  average  volume  of  milk  produced  by  these  mothers  during 
the  eleventh  to  the  thirteenth  day  after  their  infants  were  born, 
he  ascertained  to  be  440  c.c.  Weeks  or  even  months  frequently 
passed  before  the  children  regained  the  weight  which  they  had 
lost  immediately  following  birth,  when  there  was  no  evidence 
of  disease.  Kaupe  was  led  to  the  conclusion  that  artificial  feed- 
ing should  be  resorted  to  in  order  to  save  babies  failing  to  develop 
satisfactorily  on  breast  milk.  He  was  unable  to  explain  the 
nature  of  the  changes  which  rendered  the  breast  milk  inade- 
quate for  the  nutrition  of  the  infants,  and  was  inclined  to  attrib- 
ute to  psychic  influences  the  deterioration  in  its  nutritive  value. 

359.  Chemical  Composition  of  the  Milk  of  Pellagrous 
Women. — Voegtlin  and  Harris  (8)  state  that  pellagra  sometimes 
occurs  in  breast-fed  infants.  They  made  an  investigation  of 
the  milk  of  pellagrous  women  and  reported  that:  "The  volume 
may  be  normal  or  reduced,  depending  somewhat  on  the  general 
nutritional  state  and  food  consumption  of  the  patient.  Very  se- 
vere cases  often  secrete  only  100  to  300  c.c.  or  less  of  milk  per 
day,  whereas  we  have  records  of  milder  cases  which  yielded 
approximately  one  half  to  one  liter.  Lactose,  fat,  protein- 
nitrogen,  and  total  solids  were  found  to  fall  within  the  normal 
limits,  but  considerably  below  the  normal  average.  The  total 
ash  and  the  phosphate  content  were  normal.  A  slight  reduction 
in  the  quantity  of  calcium,  magnesium  and  potassium  was  noted, 
whereas  chlorids  and  sodium  were  present  in  larger  amounts. 
The  character  of  the  diet  had  no  influence  on  the  percentage  com- 
position of  the  milk,  with  the  exception  that  a  change  from  a 
vegetable  to  a  mixed  diet  was  accompanied  by  a  marked  increase 
in  the  total  non-protein  nitrogen.  The  conclusion  to  be  drawn 


THE  NUTRITION  OF  THE  SUCKLING  337 

from  these  observations  is  that  well  marked  cases  of  pellagra 
yield  a  milk,  which,  as  far  as  its  composition  with  respect  to  the 
known  milk  constituents  is  concerned,  does  not  show  a  sufficient 
deviation  from  the  normal  to  account  for  the  disease  in  nursing 
infants." 

360.  The  Effects  of  Under-Feeding  on  the  Lactating  Cow 
and  the  Composition  of  Her  Milk. — Eccles  and  Palmer  (9)  have 
conducted  a  very  thorough  experimental  study  of  the  influence 
on  milk  production  of  the  under-feeding  of  cows.    They  have 
examined  the  composition  of  milk  produced  by  cows  whose  ra- 
tions were,  from  a  qualitative  standpoint,  suitable  biologically, 
but  inadequate  in  amount.    Their  results  show  that  cows  were 
able,  during  the  early  part  of  the  lactation  period,  to  maintain 
the  milk  flow  undiminished  for  forty  days,  during  which  they  re- 
ceived but  75  per  cent  of  the  quantity  of  food  sufficient  for  their 
requirements.     Under  such  conditions  of  nutrition  there  were 
no  pronounced  changes  in  the  composition  of  the  milk.    During 
the  latter  part  of  the  lactation  period  there  was,  however,  as 
the  result  of  underfeeding,  some  falling  off  in  milk  secretion. 

361.  Deficiency   in   the   Milk   of  Women   Suffering   from 
Beri-Beri. — Interesting  evidence  on  the  effect  of  an  inadequate 
diet  in  lowering  the  nutritive  value  of  the  milk  secreted,  is 
afforded  by  the  studies  of  Andrews  (10).    It  is  well  known  that 
infants,  who  subsist  upon  the  milk  of  mothers  suffering  from 
beri-beri  resulting  from  a  simple  and  monotonous  diet  of  rice, 
fish  and  very  small  amounts  of  other  foods,  frequently  develop 
the  disease  during  the  first  few  months  of  life.    This  is  due,  in 
such  cases,  to  a  lack  in  the  milk  of  a  sufficient  quantity  of  the 
anti-neuritic  substance,  water-soluble  B.    Andrews  fed  the  milk 
of  women  suffering  from  beri-beri  to  young  pups  and  found  that 
they  soon  lost  the  use  of  the  hind  legs  and  showed  other  evidences 
of  beri-beri. 

It  will  be  seen,  therefore,  that  although  faulty  diet  in  a  lac- 
tating  female  will  not  ordinarily  modify  in  respect  to  the  ordi- 
nary components  for  which  the  chemist  has  methods  for  analysis 
the  composition  of  the  milk  which  she  secretes,  it  may  very 
easily  lower  the  nutritive  value  of  the  milk  to  such  an  extent  as 
to  render  it  unfit  food  for  an  infant.  McCollum  and  Simmonds 
(1)  have  established  experimental  conditions  which  serve  to 
illustrate  how  far  faults  of  various  kinds  and  .of  different  degrees 
in  the  diet  of  mother  rats  influence  the  rate  of  growth  in  their 
young. 

362.  A  Cereal  Diet  Is  Not  Satisfactory  for  the  Formation 


338     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

of  Normal  Milk. — It  has  been  pointed  out  that  young  animals 
do  not  grow  when  confined  to  a  single  cereal  or  other  seed  or 
mixture  of  seeds,  for  the  reason  that  these  are  all  deficient  in  the 
inorganic  elements,  calcium,  phosphorus,  sodium  and  chlorin, 
and  are  too  poor  in  fat-soluble  A  to  support  normal  nutrition. 
Likewise  the  proteins  are  too  poor  in  quality  to  maintain  satis- 
factory growth,  unless  fed  at  higher  planes  of  intake  than  can 
be  secured  with  cereal  mixtures.  McCollum  and  Simmonds  (1) 
have  studied  the  extent  to  which  the  mother  rat,  confined  to  a 
single  seed  as  the  sole  source  of  nutriment,  is  able  to  secrete  milk 
of  a  character  satisfactory  for  the  promotion  of  growth  in  her 
young.  Chart  9  shows  the  effects  of  such  diets  on  the  growth 
of  the  nursing  young. 

363.  Failure  of  the  Lactating  Rat  to  Induce  Growth  in  Her 
Young  While  Confined  to  a  Diet  of  Rolled  Oats.— The  curves 
of  rat  211  and  her  litter  of  four  young  (Chart  9)  illustrate  the 
remarkable  growth  which  the  mother  rat  is  capable  of  inducing 
in  her  offspring  when  the  diet  is  highly  satisfactory.    While  so 
doing  she  is  also  able  to  increase  her  own  weight  very  appre- 
ciably.   In  marked  contrast  to  this  "normal"  accomplishment, 
stands  the  failure  of  rat  738  to  induce  in  her  young  growth  at 
more  than  one-third  the  optimal  rate,  when  restricted  to  rolled 
oats  as  her  sole  food  supply  (1).    The  drop  in  the  curve  of  the 
weight  record  of  the  young  at  the  fortieth  day  was  the  result 
of  the  death  of  the  young  at  short  intervals.    The  mother  lost 
weight  steadily,  a  fact  which  indicated  the  sacrificing  of  her 
own  tissues  for  the  preservation  of  her  young.    Rolled  oats,  like 
other  seeds  of  plants,  requires  improvement  in  respect  to  at  least 
four  dietary  factors  before  it  becomes  a  complete  food.    If  we 
regard  as  a  distinct  entity  the  organic  substance  which  plays 
an  important  role  in  regulating  the  development  of  the  bones, 
then  there  are  five  factors  in  which  the  oat  kernel  is  deficient. 
This  is  true  in  some  degree  of  all  the  other  cereal  grains  and 
legume  seeds.    These  and  similar  records  of  female  rats  confined 
to  a  single  cereal  grain  as  their  only  food,  show  clearly  that  the 
deficiencies  in  these  grains  are  sufficiently  serious  to  interfere 
with  normal  milk  production. 

364.  Effect  on  the  Quality  of  the  Milk  of  Supplementing  the 
Oat  Kernel. — A  rat  (1)  whose  diet  consisted  of  rolled  oats  sup- 
plemented with  fat-soluble  A  in  the  form  of  butter  fat,  induced 
growth  in  her  litter  of  four  at  a  rate  somewhat  greater  than  she 
could  have  done  had  she  eaten  rolled  oats  alone.    On  this  food 


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340     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

mixture  she  was  able  to  keep  them  alive  for  a  somewhat  longer 
period.  The  first  one  died  on  the  57th  day  and  the  remaining 
ones  followed  in  rapid  succession.  This  mother  lost  considerable 
weight  up  to  the  time  when  the  young  began  to  eat  of  the  oat 
and  butter  fat  diet.  Young  rats,  after  removal  from  the  mother, 
cannot  grow  on  this  diet. 

A  mother  rat  was  fed  a  diet  of  rolled  oats  to  which  was 
added  an  inorganic  salt  mixture  so  made  up  as  to  correct  the 
mineral  deficiencies  of  the  oat  kernel.  Her  diet  still  lacked  fat- 
eoluble  A  and  the  anti-rachitic  substance  and  its  proteins  were 
below  the  optimum  both  in  quality  and  quantity.  With  this 
food  her  milk  was  distinctly  better  in  quality  than  she  could 
have  secreted  had  she  been  restricted  to  either  oats  alone  or  to 
oats  and  butter  fat  or  to  oats  supplemented  with  purified  pro- 
tein. From  these  results  it  is  apparent  that  for  milk  production 
the  first  limiting  factor  in  the  oat  kernel  is  the  same  as  for 
growth  in  the  young.  That  limiting  factor  is  the  inorganic 
content  of  the  food  supply. 

365.  Inorganic  Content  of  the  Diet  Is  Very  Important  for 
the  Secretion  of  Normal  Milk. — The  importance  of  having  the 
inorganic  content  of  the  diet  properly  constituted  is  shown  espe- 
cially well  in  the  histories  of  the  mothers  983  and  1978  (1).  The 
former  was  fed  rolled  oats  supplemented  with  both  fat-soluble 
A  (supplied  as  butter  fat),  and  purified  protein  in  the  form  of 
casein.  Even  with  these  two  additions  she  was  able  to  induce 
in  her  young  less  than  half  the  normal  growth.  The  young  began 
to  die  at  the  age  of  45  days  and  succumbed  in  rapid  succession. 
Rat  1978,  on  the  other  hand,  whose  diet  consisted  of  rolled  oats 
supplemented  with  a  suitable  salt  mixture  and  butter  fat,  was 
able  to  produce  milk  which  induced  growth  in  her  litter  at  about 
two-thirds  the  maximum  rate  observed  in  the  case  of  well  fed 
mothers.  The  improvement  of  the  milk  by  the  inclusion  of  fat- 
soluble  A  in  the  diet  was  very  apparent,  since  the  young  were 
able  to  live  beyond  the  period  of  the  sixty  days  covered  by  the 
experiment.  These  observations  support  the  view  that  fat- 
soluble  A  cannot  be  synthesized  by  the  mammary  gland. 

The  experience  of  rat  1019,  Chart  9,  whose  diet  consisted 
of  rolled  oats  supplemented  with  purified  protein  and  a  suitable 
salt  mixture,  showed  that  the  mother  was  able  to  induce  in  her 
young  nearly  normal  growth  during  a  period  of  thirty  days, 
although  her  diet  was  very  poor  in  fat-soluble  A.  It  should 
be  borne  in  mind  that  the  seeds,  because  they  contain  a  small 


THE  NUTRITION  OF  THE  SUCKLING  341 

proportion  of  cellular  structures  in  addition  to  their  reserve  food 
package  in  the  endosperm,  contain  but  a  small  and  inadequate 
amount  of  fat-soluble  A.  The  mother  is  able,  when  her  diet  of 
oats  is  corrected  with  respect  to  two  factors,  protein  and  salts, 
to  concentrate  in  the  milk  the  small  amount  of  fat-soluble  A 
in  her  food,  and  perhaps  to  supplement  this  in  some  degree  with 
the  reserve  in  her  own  fatty  tissues.  In  this  way  she  is  able  to 
bring  the  young  to  a  state  of  relative  independence  while  she 
herself  is  subsisting  on  a  food  supply  not  capable  of  inducing 
any  growth  whatever  in  the  young.  There  is  abundant  experi- 
mental proof  that  when  the  protein  and  the  inorganic  contents 
of  the  diet  are  satisfactory,  animals  can  maintain  themselves  for 
a  long  period  on  a  supply  of  fat-soluble  A  too  small  to  prevent 
xerophthalmia  in  animals  whose  diets  are  more  poorly  consti- 
tuted in  respect  to  other  factors. 

366.  Milk  Secretion  Governed  by  Same  Laws  as  the  Nutri- 
tion of  the  Growing  Young. — These  records  of  nursing  mothers 
and  their  young  make  it  apparent  that  the  former  are  limited  in 
the  utilization  of  food  for  milk  production,  in  the  same  manner 
as  the  growing  young  are  limited  in  the  utilization  of  food  for 
the  construction  during  growth  of  new  tissues.    The  mother  is 
to  no  small  degree,  however,  a  factor  of  safety  for  the  young. 
It  should  be  remembered  that  the  young  rat  cannot  grow  at  all 
when  after  weaning  it  is  confined  to  the  oat  kernel  alone  or  to 
this  cereal  supplemented  with  protein,  fat-soluble  A,  or  a  salt 
mixture  alone,  or  on  a  d;3t  in  which  oats  are  supplemented  with 
both  protein  and  fat-soluble  A.    In  order  that  it  may  grow  even 
very  slowly  it  is  essential  that  both  a  salt  mixture  and  fat- 
soluble  A  be  added  to  the  oat.    It  is  not  possible  for  it  to  grow 
normally  on  such  a  mixture  unless  protein  is  also  supplied. 

367.  The  Nursing  Mother  as  a  Factor  of  Safety  for  Her 
Young. — In  the  records  of  the  mothers  on  modified  oat  diets, 
the  young  in  certain  cases  continued  to  grow  after  the  25th  day, 
at  which  age  they  may  be  safely  weaned  if  supplied  with  a  good 
food  mixture,  and  if  their  growth  was  optimal  during  the  nursing 
period.    This  fact  is  evidence  that  even  after  the  young  are  able 
to  eat  of  the  deficient  diet  from  which  the  mother  has  produced 
milk  suitable  only  for  subnormal  growth,  and  on  which  they 
would  be  unable  to  grow  at  all,  they  are  capable  of  developing 
in  a  fairly  satisfactory  manner  for  a  time  if  they  are  supplied 
with  a  small  contribution  of  their  mother's  milk  to  supplement 
the  deficient  cereal  diet.    There  can  be  no  doubt  that  they  were 


342     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

still  receiving  a  supplementary  milk  supply  from  the  mother  and 
that  this  served  to  enhance  the  incompletely  supplemented  oat 
diets  available.  Under  adverse  circumstances,  therefore,  a  young 
animal  restricted  to  an  inadequate  diet  can  be  safely  tided  over 
a  considerable  interval,  during  which  it  would  succumb  were  it 
not  for  the  peculiar  relation  between  the  mammary  gland  and 
the  blood,  through  which  it  secretes  into  the  milk  certain  nutrient 
principles  in  amounts  larger  than  those  present  in  the  food  of 
the  lactating  female. 

The  inorganic  content  of  all  the  plant  seeds  is  the  limiting 
factor  in  preventing  growth  in  young  animals  restricted  to  such 
a  diet,  and  in  determining  the  quality  of  the  milk  secreted  by  a 
female  taking  a  seed  diet.  Although  the  young,  after  reaching  a 
state  of  independence  of  the  mother,  cannot  grow  at  all  on  a 
seed  diet  unless  it  is  enhanced  with  respect  to  certain  mineral 
elements,  the  mother  is  able  to  take  such  a  diet  without  salt  addi- 
tions and  to  produce  milk  therefrom  which  is  capable  of  inducing 
at  a  slow  rate  growth  in  the  young.  It  is  apparent  that  one  of 
her  most  important  relations  to  her  dependent  offspring  lies  in 
her  capacity  to  provide  for  them  more  adequate  nutrition  than 
she  herself  may  be  able  to  secure.  This  applies  with  special 
force  to  the  inorganic  moiety  of  the  milk  she  produces  for  them. 

368.  Deficiencies  of  All  the  Cereals  Are  Comparable  as 
Material  for  the  Elaboration  of  Milk. — The  growth  curves  of 
the  young  of  mothers,  whose  diets  consisted  of  the  oat  kernel 
with  and  without  purified  food  additions,  likewise  illustrate  very 
well  the  results  observed  when  similar  experiments  were  con- 
ducted with  the  wheat  or  maize  kernel.  They  emphasize  the 
fact  that,  for  milk  production  as  well  as  for  growth,  the  cereals 
and  other  seeds  may  be  regarded  as  closely  similar  in  their  prop- 
erties. It  is  rendered  highly  probable,  therefore,  that  the  same 
analogy  in  reference  to  value  for  milk  production  runs  through 
the  series  of  food-stuffs  of  this  class.  From  chemical  analyses 
we  know  that  the  seeds,  tubers  and  fleshy  roots  qpntain  inorganic 
elements  in  proportions  and  amounts  which,  in  a  general  way, 
place  them  all  in  the  same  class.  This  is.  especially  true  with 
respect  to  their  low  content  of  calcium,  sodium  and  chlorin,  and 
in  a  lesser  degree  of  phosphorus.  We  are,  therefore,  not  to  ex- 
pect that  any  diet  derived  solely  or  nearly  so  from  these  classes 
of  foods  will  prove  very  satisfactory  for  the  production  of  milk 
of  good  growth-promoting  power.  The  farther  the  diet  falls 
short  of  the  optimal  for  milk  formation  the  greater  the  strain 


THE  NUTRITION  OF  THE  SUCKLING  343 

placed  upon  the  lactating  organism,  because  of  the  tendency  to 
self-sacrifice  with  respect  especially  to  its  inorganic  reserves. 
Under  such  circumstances  these  would  deviate  from  the  optimal 
in  the  body  fluids  and  tissues,  and  would  cause  deterioration  of 
the  maternal  vitality.  That  such  an  occurrence  is  common  there 
can  be  no  room  for  doubt. 

369.  Importance  of  the  "Protective  Foods"  in  the  Nutrition 
of  the  Nursing  Mother. — It  should  be  reiterated  that  there  are 
two  classes  of  food-stuffs,  of  peculiar  value  in  human  and  animal 
nutrition.    These  tend  strongly  to  correct  the  deficiencies  in  a 
cereal,  legume  seed,  tuber  and  fleshy  root  diet,  or  one  in  which 
in  addition  to  these  muscle  meats  are  included.    These  are  milk 
and  the  leafy  vegetables    (11).     These,  the  protective  foods, 
should  always  play  a  prominent  role  in  the  nutrition  of  man. 
Eggs  and  the  glandular  organs  of  animals  such  as  liver,  kidney, 
etc.,  serve  to  correct  partially  the  deficiencies  of  the  type  of  diet 
derived  solely  or  nearly  so  from  vegetable  foods  functioning  as 
storage  tissues,  but  they  cannot  take  the  place  of  milk  and  the 
leafy  vegetables  because  they  are  too  poor  in  calcium.    The  ob- 
servation of  Steenbock  that  certain  edible  roots  contain  consid- 
erable amounts  of  fat-soluble  A  does  not  alter  in  a  practical 
way  the  supplementary  relationship  between  the  two  classes  of 
foods  discussed,  for  the  protein  and  inorganic  factors  are  not 
much  improved  by  making  combinations  of  any  foods  of  the 
type  of  storage  tissues. 

370.  Extent  of  Self-Sacrifice  of  the  Lactating  Mother  for 
Her  Young. — The  tendency  of  the  lactating  female  to  persist 
in  secreting  milk,  even  though  deficient  in  one  or  more  respects 
as  a  food  for  the  suckling  because  of  faults  in  her  diet,  is  truly 
remarkable.    Babcock  (12)  described  experiments  in  which  he 
deprived  cows  of  common  salt  during  lactation.     The  animals 
were  not  entirely  deprived  of  salt  since  they  were  fed  on  ordi- 
nary farm  products,  all  of  which  contain  salt,  but  they  were  not 
given  any  supplementary  supply,  as  is  the  custom  among  fanners. 
In  Wisconsin  an  ordinary  grain  and  roughage  ration  does  not 
furnish  even  approximately  enough  sodium  chlorid.    Deer,  living 
on  grass  and  the  leaves  of  shrubs,  develop  such  an  appetite  for 
salt,  that,  although  they  are  by  nature  very  shy,  they  will  brave 
any  danger  to  visit  their  accustomed  salt  licks.    In  Babcock's 
experiments  the  period  of  deprivation  of  salt  varied  from  two 
to  fifteen  months.    Some  of  the  animals  died  from  lack  of  salt 
and  others  were  saved  from  death  only  by  its  administration. 


344     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

In  no  instance  was  there  any  noticeable  decrease  in  the  yield 
of  milk  until  a  short  time  before  the  cows  began  to  fail  rapidly. 
The  fat  content  of  the  milk  from  cows  suffering  from  partial 
salt  starvation  was  somewhat  higher  than  that  of  the  milk  of 
the  control  group.  Long  before  the  cows  showed  any  sign  of 
injury  from  lack  of  salt  the  milk  became  practically  chlorin- 
free.  This  illustrates  the  fact  that  common  foods  do  not  neces- 
sarily furnish  enough  of  certain  elements  to  meet  the  needs  of 
a  lactating  mother  to  enable  her  to  secrete  a  milk  of  normal 
composition.  This  is  true  of  calcium  and  probably  of  phosphorus. 

371.  Effect  of  the  Feed  of  the  Cow  on  the  Anti-scorbutic 
Properties  of  Her  Milk. — Hart,  Steenbock  and  Ellis  (13)  experi- 
mented with  the  milk  of  cows  which  had  been  confined  for  a  year 
or  more  to  rations  consisting  of  air-dried  grains  and  forage 
plants  and  which  had  never,  during  these  months,  been  allowed 
to  eat  any  fresh  or  green  food.  The  object  of  these  investigators 
was  to  determine  whether  such  milk  had  less  anti-scorbutic  value 
than  milk  derived  from  cows  provided  with  fresh  foods  of  vege- 
table origin.  Their  results  show  clearly  that  the  content  of  the 
anti-scorbutic  substance  in  milk  is  dependent  upon  the  diet. 
Summer  pasture  milk  is  much  richer  in  this  nutritive  factor  than 
milk  from  cows  fed  upon  dried  feeds.  It  is  of  special  interest  to 
mention  that  they  found  that  even  when  cows  were  restricted 
to  a  diet,  which,  because  of  drying,  had  little  anti-scorbutic 
value,  the  mammary  gland  tended  to  concentrate  a  relatively 
large  amount  of  this  factor  in  the  milk.  Thus  the  milk  from 
dry-fed  cows  protected  guinea  pigs  from  scurvy  only  when  75 
c.c.  was  given  daily,  whereas  about  50  c.c.  were  required  of  milk 
from  cows  on  pasture.  Here  we  have  further  evidence  of  the 
role  of  the  lactating  mother  in  elaborating  a  food  for  her  off- 
spring, which  is  of  better  quality  than  her  own  supply. 

Butcher  and  his  coworkers  (14)  have  conducted  a  considerable 
number  of  experiments  with  winter  and  with  summer  milks, 
which  were  secreted  by  cows  kept  on  dry  rations  and  on  green 
food,  respectively.  Their  data  make  it  evident  that  20  c.c.  of 
summer  milk  were  superior  in  anti-scorbutic  potency  to  60  c.c. 
of  winter  milk.  Their  results  showed  that  when  a  cow  passed 
from  a  green  pasture  ration  to  one  of  dry  feed,  her  milk  did  not 
immediately  undergo  deterioration  in  respect  to  its  anti-scorbutic 
value.  Only  after  a  period  of  five  to  eight  weeks  was  there  suffi- 
cient change  in  the  quality  of  the  milk  to  show  its  effects  on 
guinea  pigs.  On  ingesting  fresh  food,  the  milk  immediately  rose 


THE  NUTRITION  OF  THE  SUCKLING  345 

in  anti-scorbutic  value.  Such  experiments  as  the  ones  just  de- 
scribed illustrate  the  great  importance  of  the  character  of  the 
diet  of  the  lactating  mother  and  the  great  importance  of  the 
method  of  feeding  cows  to  be  used  for  the  production  of  milk 
destined  for  infant  feeding. 

372.  Illustrations  of  the  Gravity  of  Various  Types  of  Faulty 
Diets  on  Quality  of  Milk. — McCollum  and  Simmonds  (15)  have 
studied  the  effects  on  the  rate  of  growth  of  young  rats,  of  differ- 
ent types  of  deficiencies  in  the  diet  of  the  lactating  mother.  The 
results  are  shown  in  Tables  XI,  XIII  and  XV.  In  Table  XV  are 
shown  the  weights  of  litters  of  young  containing  different  num- 
bers and  at  various  ages  during  the  nursing  period,  as  well  as 
later  after  they  became  able  to  supplement  the  mother's  milk 
with  the  diet  on  which  she  had  nursed  her  young.  These  weights 
serve  as  normals  for  comparison  with  the  weights  of  the  young 
of  other  mothers  whose  diets  were  faulty  in  some  respect.  Table 
XIII  shows  the  effects  on  the  young  of  depriving  the  lactating 
mother  of  sufficient  calcium. 

Although  the  data  in  the  tables  are  self-explanatory,  a  few 
cases  of  marked  contrast  may  be  mentioned.  Rat  2153  had  five 
young  and  was  given  a  satisfactory  diet  while  nursing.  At  fifteen 
days  from  birth  their  collective  weight  was  137  grams.  Rat  2365 
likewise  had  five  young.  She  was  fed  a  diet  containing  but  9  per 
cent  of  protein,  two-thirds  of  which  was  derived  from  barley 
and  one-third  from  navy  beans.  When  the  young  were  eighteen 
days  old  they  weighed  collectively  but  70  grams.  The  protein 
moiety  of  this  mother's  diet  was  of  rather  poor  quality  and  she 
was  unable  for  this  reason  to  secrete  a  satisfactory  milk  supply. 

Rat  2767  on  a  normal  diet  of  good  quality  had  a  litter  of 
six  young.  At  the  age  of  nineteen  days  they  weighed  collectively 
163  grams.  On  the  other  hand,  rat  2785  on  a  diet  too  poor  in 
calcium  had  six  young,  which  at  the  age  of  twenty  days  weighed 
altogether  but  73  grams.  The  tables  afford  a  number  of  such 
contrasts  in  the  state  of  development  of  the  young  where  the 
mothers  ate  all  their  appetites  called  for  of  diets  comparable 
in  certain  cases  in  composition  to  diets  employed  by  people  in  the 
United  States.  It  is  a  highly  significant  fact  that  a  number  of 
these  diets  were  unsatisfactory  for  the  proper  nursing  of  young. 

373.  Quality  of  Milk  Falls  Off  Before  Amount  of  Secretion 
Is  Markedly  Interfered  with. — The  question  will  naturally  arise 
in  the  mind  of  the  reader  as  to  whether  the  failure  of  the  young 

[Continued  on  page  352] 


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351 


352      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

to  grow  when  nursed  by  these  mothers,  which  were  confined  to 
faulty  diets,  was  not  the  result  of  diminished  milk  production 
rather  than  of  deviation  of  the  secretion  from  the  normal  com- 
position. It  has  not  been  found  possible  to  secure  complete 
information  as  to  the  actual  amount  of  milk  which  any  of  these 
mothers  secreted.  The  records  of  studies  on  women  and  on  do- 
mestic animals,  described  in  the  early  part  of  this  chapter,  afford 
abundant  evidence  that  it  is  the  quality  which  first  falls  off. 
Only  when  the  lactating  mother  is  brought  to  the  verge  of  break- 
down, does  the  flow  of  milk  drop  to  a  low  level.  The  occurrence 
of  infantile  beri-beri  rather  than  death  from  starvation,  further 
serves  to  prove  that  it  is  milk  of  poor  quality  rather  than  of 
insufficient  quantity  which  is  responsible  for  the  high  infant 
mortality  in  those  parts  of  the  world  where  the  poorer  classes 
live  too  largely  on  food-stuffs  derived  from  muscle  meats  and 
from  plant  products,  the  biological  functions  of  which  are  those 
of  storage  organs.  (See  Chart  X.) 

374.  Breast  Milk  Not  a  Satisfactory  Food  Unless  the  Diet 
of  the  Mother  Is  Good. — The  statement,  reiterated  so  frequently, 
that  breast-feeding  of  infants  is  superior  to  the  best  system  of 
artificial  feeding  needs,  however,  some  modification.  There  are 
many  women  in  various  parts  of  the  world  whose  diets  are  suffi- 
ciently faulty  to  interfere  with  the  secretion  of  milk  of  good 
quality,  and  they  accordingly  supply  their  babies  a  food  which 
must  necessarily  lead  to  retardation  of  development.  An  ex- 
treme case  was  observed  by  Andrews  in  certain  women  in  the 
Philippine  Islands,  whose  infants  developed  paralysis  and  died 
of  beri-beri.  The  pathological  condition  was  due  to  the  fact 
that  the  mothers,  while  nursing,  restricted  themselves  to  a  diet 
of  a  deficient  type. 

The  carnivorous  mother  can  produce  milk  of  good  quality 
when  her  diet  contains  sufficient  amounts  of  glandular  organs 
and  bone  in  addition  to  muscle,  blood  and  fat,  but  not  otherwise. 
The  omnivorous  mother,  to  which  class  the  human  mother  be- 
longs, but  too  frequently  attempts  to  nurse  her  infant  while  she 
subsists  on  a  diet  of  muscle  meats,  bread  made  from  degermi- 
nated  and  decorticated  cereal,  and  potatoes  and  a  few  other 
articles  which  have  analogous  dietary  insufficiencies.  The  occa- 
sional occurrence  of  scurvy  in  breast-fed  infants  represents  an 
extreme  example  of  specific  starvation  of  the  mother  for  a  single 
dietary  factor,  and  the  resulting  deterioration  of  her  nursing 
infant.  Physicians  and  nurses  have  repeatedly  reported  to  me 


353 


354     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

their  observations  that  many  women  while  nursing  infants  take 
for  days  or  weeks,  diets  derived  in  great  measure  from  tea,  toast, 
sugar  and  other  articles  of  food  equally  unfit  for  the  elaboration 
of  milk.  The  nursing  mother  should  always  have  a  diet  of  a 
quality  calculated  to  insure  a  satisfactory  composition  of  the 
milk  which  she  is  to  secrete.  This  she  can  best  realize  by  in- 
cluding in  her  menus  liberal  amounts  of  milk  and  of  salads.  It 
is  not  enough  for  the  diet  to  yield  a  proper  calorific  value,  fur-' 
nish  protein  according  to  the  long  accepted  standards,  and  afford 
variety  and  palatability.  The  specific  dietary  properties  of  the 
food  mixtures  which  enter  into  the  diet  are  of  paramount  im- 
portance and  must  be  given  due  and  weighty  consideration. 

375.  Rickets  May  Occur  in  Breast-Fed  Infants  when  the 
Mothers'  Diet  Is  Faulty  in  Certain  Ways. — Attention  should 
again  be  turned  to  the  observations  of  Hess  (16)  that  the  negro 
women  of  the  Columbus  Hill  District  in  New  York  City,  whose 
diets  are  derived  almost  exclusively  from  milled  cereal  products, 
tubers  and  muscle  meats,  fail  to  nourish  their  infants  satisfac- 
torily, as  is  shown  by  the  almost  universal  prevalence  of  rickets 
among  them.    Because  of  the  limited  capacity  of  the  digestive 
tract,  it  is  difficult  for  the  human  being  to  correct  the  deficiencies 
of  these  products  by  the  consumption  of  leafy  vegetables  as  the 
sole  protective  foods.    Milk  is  the  most  satisfactory  adjuvant  to 
the  diet  of  the  nursing  mother  for  the  correction  of  whatever 
deficiencies  it  is  likely  to  exhibit  in  inorganic  elements,  quality 
of  protein,  and  fat-soluble  A.  The  inclusion  of  moderate  amounts 
of  raw  fruits  and  of  raw  salad  leaves  and  vegetables,  is  the  best 
procedure  for  making  available  a  satisfactory   amount  of  the 
anti-scorbutic  substance  in  mother's  milk. 

376.  All  Who   Escape   Recognizable   Nutritional   Disease 
Are  Not  Well  Nourished. — It  is  of  great  importance  to  appre- 
ciate the  fact  that  there  may  occur  by  reason  of  faulty  diet 
serious  damage  to  the  young  without  the  development  of  symp- 
toms which  definitely  mark  the  patient  as  a  sufferer  from  a  defi- 
ciency disease.    The  latter  cases  are  the  rare  exception.     The 
most  serious  situation  is  that  of  hosts  of  children  who  suffer 
physical  inferiority,  and  perhaps  mental  inferiority,  abnormal- 
ity of  form  and  lowered  vitality  as  the  result  of  failure  to  secure 
in  infancy  and  childhood  a  diet  adequate  to  their  needs.    These 
children  represent  border-line  conditions  which  usually  pass  un- 
noticed as  cases  of  malnutrition.     These  are  the  children  who 
frequently  find  their  way  into  the  school  clinics  and  are  forced 


THE  NUTRITION  OF  THE  SUCKLING  355 

to  repeat  their  work  in  one  or  more  of  the  grades,  and  whose 
teeth  serve  as  a  source  of  lifelong  annoyance.  I  do  not  desire 
to  minimize  the  importance  of  the  after-effects  of  infectious 
diseases  as  a  factor  in  swelling  the  number  in  this  type  of  chil- 
dren. In  a  very  large  number  of  cases,  however,  there  can  be 
no  longer  any  reasonable  doubt  that  the  most  fundamental  prob- 
lem is  that  of  securing  for  these  children  a  wisely  planned  diet 
calculated  to  raise  their  vitality  to  a  higher  plane. 

377.  The  Problem  of  Preventive  Dentistry  Largely  One  of 
Feeding  During  Infancy  and  Childhood. — In  an  earlier  chapter 
it  has  besn  shown  how  easily  deviations  from  the  optimal  compo- 
sition o-£  the  diet  with  respect  to  certain  factors,  leads  to  the 
development  in  the  bones  of  histological  changes  easily  demon- 
strable. These  changes  are  prominent  in  rickets  and  kindred 
conditions.  It  should  be  fully  appreciated  by  all,  that  the  process 
of  enamel  development  in  the  teeth,  their  eruption  and  nutrition 
is  a  part  of  the  development  of  the  osseous  system,  and  is  affected 
by  the  same  factors  that  influence  bone  growth.  If  a  tooth  is 
poorly  made,  the  best  that  can  be  done  for  its  preservation  is 
frequent  repair.  Teeth  are  developed  and  enameled  before  they 
are  erupted,  and  these  events  take  place  during  the  last  months 
before  birth  and  following  birth.  During  infancy  the  perma- 
nent teeth  develop  just  under  the  milk  teeth.  The  importance 
of  providing  at  this  epoch  in  the  life  of  the  child,  an  uninter- 
rupted state  of  nutrition  which  is  as  nearly  the  optimal  as 
possible,  will  serve  as  the  most  effective  measure  in  providing 
in  the  child  a  dental  equipment  which  will  last  well  into  old  age 
and  protect  against  the  danger  of  invasion  by  microorganisms 
which  now  so  frequently  cause  serious  infections.  Although  it 
may  sound  prophetic  at  this  time,  when  we  have  become  so 
thoroughly  schooled  in  referring  almost  exclusively  the  health 
problems  of  the  human  race  to  the  field  of  bacteriology  and 
parasitology,  I  cannot  close  this  discussion  without  asserting 
that  there  is  an  even  more  fundamental,  indispensable  feature  of 
health  promotion  than  these.  The  basis  for  everything  that  is 
worth  while  in  life  lies  in  physical  vigor,  and  as  a  means  of  se- 
curing for  the  young,  the  adult  of  the  future,  this  priceless 
treasure,  the  importance  of  a  properly  adjusted  dietary  can 
scarcely  be  over-emphasized  (17). 

This  chapter  on  the  nursing  mother  strikes  the  keynote  of  this 
book,  for  it  affords  proof  of  the  existence  of  and  points  the  way 
to  the  remedy  for  one  of  the  greatest  sources  of  human  inefii- 


356      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

ciency  and  suffering.  Moreover,  touching  as  it  does  the  root  of 
the  evil  effects  of  one  of  the  most  colossal  errors  of  civilization, 
this  chapter  serves  to  illustrate  most  vividly  the  far-reaching 
importance  of  scientific  nutrition  in  preventive  medicine. 


BIBLIOGRAPHY 

1.  McCollum,  E.   V.,   Simmonds,   N.,   and   Pitz,   W.:     The   relation   of 

unidentified  dietary  factors,  fat-soluble  A  and  water-soluble  B,  of 

the  diet  to  the  growth  promoting  properties  of  the  milk,  Jour.  Biol. 

Chem.,  1916,  xxvii,  33. 
McCollum,  and  Simmonds:     The  nursing  mother  as  a  factor  of  safety 

in  the  nutrition  of  the  suckling,  Amer.  Jour.  Physiol.,  1918,  xlvi, 

275.    Also  unpublished  data. 
2.  Osborne,  T.  B.,  and  Mendel,  L.  B.:     The  role  of  gliadin  in  nutrition, 

Jour.  Biol.  Chem.,  1912,  xii,  473. 
Hart,  E.  B.,  Nelson,  V.  E.,  and  Pitz,  W.:     Synthetic  capacity  of  the 

mammary  gland.    1.   Can  the  gland  synthesize  lysin?,  Jour.  Biol. 

Chem.,  1918,  xxxvi,  291. 

3.  McCollum,  E.  V.,  and  Davis,  M.:     The  necessity  of  certain  lipins  in 

the  diet  during  growth,  Jour.  Biol.  Chem.,  1913,  xv,  175. 

4.  Osborne,    and    Mendel:      Further    observations    on   the    influence    of 

natural  fats  on  growth,  Jour.  Biol.  Chem.,  1915,  xx,  379. 

5.  Decaisne,   E.:      Ueber   die    Veranderungen,    welche    die    Frauenmilch 

erleidet  in  Folge  unvollstandiger  Ernahrung,  Gazette  medec.  de 
Paris,  1871,  317. 

6.  Momm,  and  Kraemer:     Hat  der  Krieg  einen  Einfluss  auf  die  Zusam- 

mensetzung  der  Frauenmilch?,  Miinchen.  med.  Wochenschr.,  1917, 
Ixiv,  1419. 

7.  Kaupe,    W.:      Muttermilch    und    Krieg,    Monatschrift    fur    Kinder- 

heilkunde,  Orig.  1918-19,  xv,  83.    Leipzig  u.  Wien. 

8.  Voegtlin,  C.,  and  Harries,  R.  H.:     The  occurrence  of  pellagra  in  nurs- 

ing infants  with  observations  on  the  chemical  composition  of  human 
milk  from  pellagrous  mothers,  U.  S.  Public  Health  Service,  Hyg. 
Lab.  Bull.  No.  116,  1920. 

9.  Eccles,  C.  H.,  and  Palmer,  L.  S.:     The  influence  of  parturition  on  the 

composition  and  properties  of  the  milk  and  milk  fat  of  the  cow, 
Jour.  Biol.  Chem.,  1916,  xxvii,  313. 

10.  Andrews,  V.  L.:    Infantile  beri-beri,  Philippine  Jour,  of  Sci.,  Series  B., 

1912,  vii,  67. 

11.  McCollum,  and  Simmonds:     The  American  Home  Diet,  An  Answer 

to  the  Ever  Present  Question:  What  shall  We  have  for  Dinner?, 
Detroit,  1920. 

12.  Babcock,  S.  M.:     Wisconsin  Agr.  Exper.  Sta.  Ann.  Report  1905,  129. 

13.  Hart,  E.  B.,  Steenbock,  H.,  and  Ellis,  N.  R.:     Influence  of  diet  on 

the  anti-scorbutic  potency  of  milk,  Jour.  Biol.  Chem.,  1920,  xlii,  383. 
Hart,   Steenbock,  and   Smith:     Effect   of  heat   on  the   anti-scorbutic 

properties  of  some  milk  products,  Ibid.,  1918-19,  xxxviii,  305. 
Hart,  Steenbock,  and  Ellis:     Anti-scorbutic  potency  of  milk  powder, 

Ibid.,  1921,  xlvi,  309. 


EH  5  "J 


111 


THE  NUTRITION  OF  THE  SUCKLING  357 

14.  Butcher,  R.  A.,  Eccles,  C.  H.,  Dahle,  C.  D.,  Mead,  S.  W.,  and  Schaefer, 

0.  G. :  The  influence  of  diet  of  the  cow  upon  the  nutritive  and 
anti-scorbutic  properties  of  cow's  milk,  Jour.  Biol.  Chem.,  1920-21, 
xlv,  119. 

15.  McCollum  and  Simmonds:  Unpublished  data. 

16.  Hess,  A.  F.,  and  linger,  L.  J.:     The  diet  of  the  negro  mother  in  New 

York  City,  Jour.  Amer.  Med.  Assn.,  1918,  Ixx,  900,  March  30. 
Hess,  A.  F.,  Unger,  L.  J.,  and  Supplee,  G.  C.:     Relation  of  fodder  to 
the  anti-scorbutic  potency  and  the  salt  content  of  milk,  Jour.  Biol. 
Chem.,  1920-21,  xlv,  229. 

17.  King,  E.  Truby :    The  story  of  the  teeth  and  how  to  save  them,  London. 

The  natural  feeding  of  infants,  London,  1918. 


CHAPTER  XVI 

NEW  VIEWPOINTS  RELATING  TO  PRACTICAL 
PROBLEMS  OF  NUTRITION 

378.  The  Importance  of  Animal  Experimentation  to  Human 
Welfare. — The  sciences  of  medicine  and  surgery  are  built  upon 
experience  gained  through  animal  experimentation.  Almost  all 
our  knowledge  of  the  role  which  bacteria  play  in  the  production 
of  disease  has  been  gained  through  studies  on  the  lower  animals. 
Protective  serums  could  never  have  been  discovered  except  by 
such  procedure.  Even  now  it  is  possible  to  diagnose  some  of  the 
diseases  most  harmful  to  man  only  by  the  employment  of  rabbits 
or  guinea  pigs  as  test  subjects,  or  for  the  production  of  blood 
having  special  properties  for  use  in  making  laboratory  tests. 

The  latest  branch  of  medicine  to  develop  is  inspired  by  the 
prospect  of  preventing  disease  instead  of  the  old  ideal  of  curing 
the  sick.  This  new  field  of  preventive  medicine  owes  much  to 
animal  experimentation.  Natural  vitality  enables  the  tissues  to 
resist  the  entrance  of  certain  bacteria,  and  constitutes  a  most 
effective  defence  for  the  body  against  many  agencies  to  which 
in  an  enfeebled  condition  it  would  succumb.  Our  knowledge  of 
the  profound  effect  which  the  diet  may  exert  on  the  vigor  of  the 
body  is  almost  entirely  the  product  of  observations  of  the  effects 
of  specially  planned  experiments  on  small  animals. 

The  study  of  the  science  of  nutrition  as  a  branch  of  preventive 
medicine  has  not  been  sufficiently  appreciated  in  the  past.  It  is 
true  that  the  carbohydrate  content  of  the  diet  of  the  diabetic  has 
for  many  years  been  regulated  as  a  therapeutic  measure.  Food 
has  been  selected  with  a  view  to  the  relief  of  constipation. 
Liquid  or  soft  diets  have  been  provided  for  the  sick  in  certain 
conditions.  Anti-scorbutic  foods  have  been  provided  for  persons 
who  were  subjected  to  conditions  which  experience  had  shown 
were  likely  to  induce  scurvy.  The  avoidance  of  excessive  food 
consumption  has  been  recommended.  A  low  protein  diet,  a 
purin-free  diet,  sour  milk  as  a  therapeutic  agent,  and  other 
dietetic  regulations  have  been  resorted  to  as  means  of  affording 
nourishment  specially  suited  to  peculiar  conditions. 

358 


NEW  VIEWPOINTS  OF  NUTRITION  359 

379.  Nutrition  Has   Assumed  Greater  Importance   Than 
Ever   Before. — In  recent  years,   however,  new   and  surprising 
relations  between  food  and  health  have  become  apparent.    The 
relation  between  polished  rice  and  beri-beri  has  been  brought  to 
light.     Observations  on  the  sequence  of  events  as  famine  condi- 
tions are  approached,  have  established  the  fact  that  as  the  last 
reserves  of  food  are  drawn  upon  epidemics  of  dropsy,  cholera, 
pellagra,  etc.,  develop  and  carry  off  the  semi-starved  population 
before  they  have  time  to  die  of  starvation.     The  greatly  in- 
creased sickness  and  mortality  rates  among  civilians  in  warring 
countries  has   often  been   attributed  to  under-nutrition  or  to 
faulty  diet,  but  the  causes  which  brought  about  these  conditions 
were  understood  only  in  a  vague  way.    The  debilitating  influence 
of  lack  of  sufficient  food  is  easy  for  anyone  to  appreciate,  but 
an  understanding  of  the  gravity  of  restriction  to  diets  which  are 
faulty  in  their  chemical  composition  only  in  minor  degrees  is 
less  easily  acquired.     Many  well  informed  people  who  are  ac- 
customed to  the  critical  examination  of  data  have  not  infre- 
quently shown  a  lamentably  superficial  conception  of  the  rela- 
tion of  the  character  of  the  diet  to  health  conditions. 

380.  Many  Are  Still  Unable  to  Grasp  the  Fundamentals  of 
Scientific   Nutrition. — To-day   few  would   dare  to   reject  the 
array  of  experimentally  established  facts  and  deny  the  relation 
of  beri-beri  or  scurvy  to  lack  of  some  essential  substances  in  the 
diet,  or  question  that  there  is  a  high  degree  of  specificity  in  the 
effects  of  the  missing  constituents  which  induce  the  development 
of  these  syndromes.    Many,  however,  who  consider  themselves 
capable  of  passing  sound  critical  judgment  on  health  matters 
have  attributed  some  of  the  nutritive  disturbances  seen  in  cer- 
tain parts  of  Europe  during  the  great  war,  to  lack  of  sufficient 
fat  in  the  diet  when  the  latter  was  derived  in  great  measure 
from  cereals  and  potatoes,  and  have  felt  satisfied  with  thus  dis- 
posing of  the  matter.     In  so  doing  they  have  ignored  several 
other  defects  in  such  a  restricted  food  supply  which  have  within 
recent  years  become  clearly  demonstrated,  but  are  still  not  gen- 
erally understood.     The  experimental  data  discussed  in  earlier 
chapters  leaves  but  small  room  for  doubt  that  lack  of  fats, 
strictly  speaking,  had  little  or  nothing  to  do  with  health  condi- 
tions.   It  was  a  lack  of  the  substance  fat-soluble  A,  which  cer- 
tain fats  of  animal  origin  contain  in  abundance,  but  which 
vegetable  fats  and  oils  derived  from  oil-bearing  seeds  either  lack 
entirely  or  at  best  supply  but  very  inadequate  amounts,  which 


360      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

was  responsible  for  such  nutritive  disturbances  as  could  be 
attributed  to  lack  of  fats  in  the  diet.  This  view  is  supported  by 
the  observation  of  Wells  (1),  who  observed  remarkable  benefit 
through  the  administration  of  small  amounts  of  cod  liver  oil  to 
malnourished  Roumanians  whose  eyes  were  damaged  by  faulty 
diet.  In  many  places,  it  would  doubtless  have  been  possible 
under  wise  management,  to  have  corrected  the  defect  due  to  lack 
of  fat-soluble  A  in  the  diet  by  a  liberal  use  of  leafy  vegetables, 
although  these  contain  no  more  fats  than  do  the  cereals. 

There  were  operating  at  the  same  time  to  produce  malnutri- 
tion, other  factors  essentially  as  important  as  the  lack  of  fat- 
soluble  A  in  the  diets  just  described.  These  were  a  low  intake 
of  protein  of  relatively  low  biological  value,  and  lack  of  suffi- 
cient amounts  of  certain  mineral  elements,  especially  calcium  and 
phosphorus  and  a  low  anti-scorbutic  value  of  the  foods  employed. 
These  deficiencies  were  doubtless  on  a  parity  with  lack  of  fat- 
soluble  A  in  causing  lowered  vitality,  ill-defined  cravings  of  the 
appetite,  gastro-intestinal  disturbances,  and  interruption  of 
growth  and  faulty  skeletal  development  in  children. 

381.  There  Is  Need  of  Popularizing  the  New  Knowledge 
of  Nutrition. — The  lack  of  understanding  of  the  way  to  solve  the 
practical  problems  of  alimentation  which  were  forced  upon 
Europe  by  the  war  is  easily  appreciated  when  we  consider  how 
new  the  science  of  nutrition  is.  The  literature  relating  to  the 
phases  of  the  subject  which  were  understood  was  confined  to 
scientific  journals.  Few  of  the  men  who  became  officials  in  the 
armies  had  any  knowledge  of  nutrition  other  than  that  relating 
to  calorific  and  protein  requirements.  Under  the  trying  condi- 
tions of  war  there  was  little  time  or  opportunity  to  acquire  or 
apply  new  knowledge,  and  no  great  incentive  to  seek  anything 
beyond  bare  subsistence  except  in  those  members  of  the  popula- 
tion who  contributed  directly  in  some  manner  to  military  success. 

It  is  not  easy  to  overlook  the  short-sightedness  and  to  forgive 
the  damaging  propaganda  of  certain  specialists  concerned  with 
public  health  work  who  hold  that  there  is  no  reason  to  believe 
that  there  is  any  important  relation  between  the  character  of 
the  diet  and  the  health  of  the  individual  except  under  circum- 
stances where  the  faults  of  the  diet  are  extreme.  Some  have 
insisted  that  the  great  increase  of  tuberculosis  in  Europe  since 
1914  is  no  evidence  that  under  conditions  more  nearly  approach- 
ing normal,  the  character  of  the  diet  is  a  factor  of  importance 
in  predisposing  one  to  this  disease.  The  view  is  held  that  at  a 


NEW  VIEWPOINTS  OF  NUTRITION  361 

certain  point  of  severity  in  malnutrition  the  vitality  breaks  down, 
and  the  body  becomes  a  prey  to  diseases  due  to  the  invasion  of 
micro-organisms,  but  that  up  to  this  critical  point  the  diet  plays 
little,  if  any,  role  in  the  etiology  of  infectious  diseases.  There 
is  much  reason  to  believe  that  this  conception  is  not  generally 
applicable  and  that  it  applies  only  to  a  certain  group  of  infec- 
tions. There  are  many  gra'des  of  malnutrition  between  the 
optimum  well-being  on  the  one  hand  and  on  the  other,  such  ex- 
treme conditions  as  are  recognizable  by  the  clinician. 

382.  Entire  Subject  Must  Be  Viewed  from  a  New  Angle. — 
In  order  to  appreciate  the  viewpoint  which  is  established  by 
recent  researches  on  foods  and  nutrition  it  is  essential  to  fully 
understand  the  great  advantages  which  we  now  enjoy  in  being 
able  to  think  of  foods  in  an  entirely  different  way  from  what 
was  possible  a  few  years  ago.     Ten  years  ago  the  crude  com- 
parison of  alimentation  with  the  stoking  of  an  engine  seemed 
satisfactory  to  most  teachers.    This  is  no  longer  a  suitable  figure 
for  conveying  to  the  student  of  nutrition  the  conception  which  it 
is  desired  he  should  gain.    Little  more  than  a  decade  ago  it  was 
supposed  that  a  chemical  analysis  of  a  food  for  protein,  carbo- 
hydrate, fat  and  mineral  salts,  was  sufficient  to  reveal  its  bio- 
logical properties.    Certain  standards  of  composition  had  become 
established  on  the  authority  of  experts,  and  it  was  believed  that 
if  any  food  fulfilled  the  requirements  of  these  standards  with 
respect  to  total  digestible  nutrients,  available  energy  and  pro- 
tein content,  it  could  be  counted  upon  to  meet  the  nutritive 
requirements  of  the  body.    In  Chapter  II  it  has  been  described 
how  after  the  year  1900  many  attempts  to  nourish  young  animals 
on  food  mixtures  made  up  of  purified  substances,  and  including 
the  approved  amounts  of  all  the  components  of  foods  which  the 
chemist  was  called  upon  to  estimate,  proved  utter  failures,  and 
demonstrated  the  inadequacy  of  a  time-honored  theory. 

383.  Types    of   Experimental    Observations   which    Made 
Nutrition  a  New  Science. — The  early  experimental  work  with 
diets  consisting  of  relatively  pure  food  substances  had  for  their 
objective  in  many  instances,  the  demonstration  of  the  inadequacy 
of  such  "incomplete"  proteins  as  gelatin  or  zein,  or  the  relative 
merits  of  phosphorized  and  non-phosphorized  proteins.     There 
was  a  period  when  a  series  of  papers  were  published  by  physi- 
ological chemists  debating,  on  the  basis  of  rather  poorly  planned 
experimental  work  and  its  results,  the  question  as  to  whether 
phosphorus  in  the  form  of  organic  compounds  such  as  lecithins, 


362      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

or  phosphorized  fats,  the  nucleic  acids  found  in  the  nuclei  of 
cells,  and  in  phosphorized  proteins  such  as  casein  of  milk  or 
vitellin  of  egg  yolk,  was  superior  in  its  nutritive  value  to  the 
phosphorus  of  mineral  salts  such  as  calcium  phosphate.  The 
view  was  supported  that  for  the  construction  of  the  highly  or- 
ganized structures  of  the  body  tissues  such  as  nuclear  substance, 
complex  phosphorus-containing  fats,  etc.,  it  was  essential  that 
similar  highly  organized  phosphorus  compounds  should  be  avail- 
able in  the  food.  It  was  generally  conceded  that  bone  could  be 
formed  from  inorganic  phosphates,  but  most  investigators 
doubted  whether  this  form  was  as  valuable  as  organic  phos- 
phorus in  animal  nutrition.  This  subject  was  for  years  a  promi- 
nent one  for  discussion,  although  there  never  was  a  single  well 
established  fact  to  support  the  view  that  the  highly  organized 
forms  of  this  element  which  occur  in  plant  and  animal  tissues 
are  superior  in  animal  nutrition  to  the  simple  mineral  salts  of 
phosphorus.  In  1909,  as  has  already  been  described  (2),  Mc- 
Collum  first  published  experimental  work  which  finally  dis- 
posed of  this  entire  question,  by  showing  that  young  rats  could 
grow  on  diets  containing  phosphorus  only  in  the  form  of  cal- 
cium phosphate  derived  by  grinding  the  naturally  occurring 
mineral. 

384.  The  Experiments  of  Hopkins. — The  experiments  of  one 
investigator,  Hopkins  (3),  were  of  a  different  type  from  those 
mentioned  in  the  preceding  paragraph.  He  met  with  complete 
failure  in  his  attempts  to  nourish  young  animals  on  purified  pro- 
tein, carbohydrates,  fats  and  mineral  salts,  but  was  able  to  induce 
growth  with  the  same  diet  supplemented  with  small  additions 
of  milk.  The  milk  furnished  some  substance  or  substances 
which  were  not  present  in  the  mixture  of  purified  food  substances, 
and  which  were  essential  for  growth  or  the  maintenance  of 
health.  It  has  been  pointed  out  how  Hopkins  recognized  the 
significance  of  his  discovery  and  designated  the  unknown  sub- 
stance or  substances  which  the  milk  furnished  to  the  advantage 
of  his  animals,  as  "accessory"  food  substances.  These  experi- 
ments were  conducted  in  1906  but  were  not  described  until  1912. 
In  the  meantime  Hoist  had  made  his  classic  demonstration  of 
the  relation  of  scurvy  to  diet,  and  Funk  and  Suzuki  had  come 
forward  with  their  extension  of  the  studies  of  Eijkman  and  of 
Schaumann,  and  had  coined  the  terms  "vitamine"  and  "ory- 
zanin"  respectively.  In  the  minds  of  many  nutrition  investi- 
gators these  were  observations  in  the  field  of  pathology  rather 
than  of  normal  nutrition. 


NEW  VIEWPOINTS  OF  NUTRITION  363 

The  results  of  the  feeding  experiments  with  cattle  described 
in  Chapter  II  are  sufficient  to  illustrate  the  fact  that  studies  with 
ordinary  foods  such  as  wheat,  maize,  etc.,  could  never  have  been 
made  to  reveal  the  secrets  which  lay  hidden  in  the  field  of  nutri- 
tion. The  results  of  those  studies  amply  demonstrated  that 
the  persistent  efforts  of  McCollum  and  Davis  from  1907  to  1915 
in  seeking  to  discover  the  reason  for  the  failure  of  young  ani- 
mals to  grow  on  diets  consisting  of  purified  food  substances  was 
the  most  profitable  line  of  attack  for  securing  an  insight  into 
the  number  and  natures  of  the  factors  which  enter  into  the 
make-up  of  an  adequate  diet. 

385.  Difficulties  of  Solution  of  the  Fundamental  Problems 
of  Nutrition. — Simple  as  the  discussion  of  the  adequate  diet  ap- 
pears to  be  in  the  present  state  of  our  knowledge,  it  was  a  most 
difficult  task  to  bring  order  and  understanding  into  the  field  of 
nutrition.  In  experiments  with  the  rat  using  simplified  and  puri- 
fied food  substances  such  as  were  necessary  for  solving  the  prob- 
lems of  what  constitutes  the  simplest  adequate  diet,  the  difficulty 
in  succeeding  was  much  greater  than  one  would  at  first  thought 
suppose.  The  small  prospect  of  success  will  be  better  appre- 
ciated when  it  is  realized  that  there  were,  for  the  nutrition  of 
the  rat,  two  indispensable  dietary  factors  whose  existence  were 
hardly  more  than  suspected  by  students  before  that  time.  These 
were  the  anti-ophthalmic  and  anti-neuritic  substances,  fat-solu- 
ble A  and  water-soluble  B,  respectively.  In  addition  there  were 
three  variable  factors  whose  importance  was  appreciated  in  a 
general  way,  but  for  which  no  satisfactory  standards  had  been 
established.  These  related  especially  to  the  quality  of  the  pro- 
tein, the  concentration  of  the  several  mineral  elements  essential 
to  normal  nutrition,  especially  calcium  and  phosphorus,  but  also 
in  an  important  degree  to  the  content  of  sodium  and  chlorin  in 
the  diets.  Any  one  or  more  of  these  factors  might  easily  be  so 
constituted  as  to  determine  the  failure  or  success  of  an  experi- 
ment. If  the  purified  protein  happened  to  be  of  relatively  poor 
quality,  the  amount  of  it  included  in  the  diet  might  easily  be 
too  scanty  to  support  growth,  yet  it  would  be  impossible  except 
through  the  conduct  of  a  considerable  number  of  experiments, 
to  gain  a  satisfactory  insight  into  this  matter.  If,  in  deciding 
on  the  amount  of  calcium  to  introduce  into  an  experimental 
diet,  it  was  assumed  that  a  cereal,  such  as  wheat,  probably  con- 
tained a  proper  amount  to  meet  the  nutritive  needs  of  an  animal, 
this  error  would  have  foredoomed  the  resulting  growth  experi- 
ment to  failure,  even  if  an  abundance  of  protein  of  good  quality, 


364     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

and  vitamins  in  liberal  amounts  were  supplied,  and  satisfactory 
adjustment  of  every  other  constituent  of  the  food  was  by  good 
fortune  realized.  A  similar  statement  may  also  be  made  re- 
garding phosphorus,  but  the  shortage  of  this  element  is  not  so 
serious  in  most  vegetable  or  animal  foods,  and  if  the  investi- 
gator was  guided  by  the  content  of  phosphorus  in  ordinary 
cereals  in  arriving  at  a  decision  as  to  how  much  of  this  element 
to  include,  a  less  serious  error  was  likely  to  be  made.  Even 
the  failure  to  add  a  sufficient  amount  of  common  salt  would 
have  been  disastrous  to  such  experiments  as  we  are  discussing, 
the  object  of  which  was  to  find  just  what  elements  and  com- 
plexes are  indispensable  in  a  diet,  and  to  prepare  the  simplest 
possible  food  mixture  which  could  support  growth  and  normal 
well-being.  Such  studies  required  much  time  and  labor  in  the 
preparation  of  carefully  purified  substances,  and  failure  in  a 
considerable  number  of  attempts  would  be  expected  to  lead  to 
discouragement  and  cessation  of  effort  to  solve  such  a  problem 
since  the  chances  of  success  would  seem  so  remote. 

When  it  is  appreciated  that  there  was  no  other  possible  method 
of  attacking  the  solution  of  this  problem  than  the  conduct  of  a 
series  of  feeding  experiments  with  simplified  diets,  and  the 
interpretation  of  the  results  on  the  basis  of  whether  the  ani- 
mals in  numerous  groups  grew  or  failed  to  grow,  it  will  be  con- 
ceded that  the  prospects  of  succeeding  in  arriving  at  an  under- 
standing of  the  essentials  and  non-essentials  of  an  adequate  diet 
were  very  remote.  By  good  fortune,  however,  this  problem  was 
successfully  solved  in  its  broad  outlines,  and  further  detailed 
researches  can  now  be  undertaken  with  definite  aims  and  the 
guidance  of  an  adequate  theory. 

386.  The  Method  of  Interpretation  of  McCollum  and  Davis. 
— In  1915  McCollum  and  Davis  published  two  papers  which 
described  a  satisfactory  method  for  interpreting  such  experi- 
ments. They  gave  two  convincing  demonstrations  of  the  ap- 
plicability of  their  theory  of  interpretation,  which  has  formed 
the  basis  of  all  the  more  important  nutrition  studies  since  that 
time.  One  of  these  was  a  description  of  a  successful  growth 
experiment  with  young  rats  fed  a  diet  consisting  of  purified  pro- 
tein, carbohydrate  and  mineral  salts  supplemented  with  such  a 
fat  as  butter  fat,  together  with  an  extract  of  a  natural  food 
which  contained  the  anti-neuritic  substance.  The  same  diet 
without  the  extract  proved  a  failure,  as  it  also  did  when  a 
vegetable  fat  or  the  body  fat  (lard)  of  animals  replaced  the 


NEW  VIEWPOINTS  OF  NUTRITION  365 

butter  fat.  An  adequate  amount  of  fat  was  not  the  necessary 
element,  but  rather  the  right  kind  of  fat,  or  fat  which  contained 
in  solution  some  substance  which  is  essential  for  the  normal 
functioning  of  the  body.  This  experiment  demonstrated  also 
that  a  second  substance,  the  anti-neuritic  factor,  was  equally 
indispensable  with  the  one  furnished  by  butter  fat.  The  second 
demonstration  of  the  validity  of  the  view  which  was  expressed 
as  to  the  essential  components  of  a  diet  was  made  with  polished 
rice.  It  was  clearly  shown  that  in  order  to  make  this  degermi- 
nated  and  decorticated  food  grain  complete  from  the  dietetic 
standpoint  it  was  essential  to  supplement  it  with  a  protein  to 
make  good  the  shortage  of  this  factor;  with  certain  mineral  salts, 
and  with  a  growth-promoting  fat  and  an  extract  which  fur- 
nished the  anti-neuritic  substance. 

387.  It  Was  a  Piece  of  Good  Fortune  That  the  Earliest 
Experimental  Studies  Were  Made  with  the  Rat. — It  is  further 
of  interest  to  point  out,  in  the  light  of  our  present  knowledge 
that  if  the  rat  had  been  susceptible  to  the  disease  scurvy,  these 
experiments  would  both  have  ended  in  failure  and  no  possible 
explanation  would  have  been  apparent,  for  in  both  cases  the 
series  of  diets  employed  were  lacking  in  the  anti-scorbutic  sub- 
stance which  is  essential  for  the  normal  nutrition  of  certain 
species  such  as  man,  monkey  and  guinea  pig.    Fortunately  for 
progress  in  this  branch  of  science,  the  rat  is  immune  to  scurvy, 
because  he  can  synthesize  the   anti-scorbutic   substance   from 
other  complexes   in  the   food.    For  the  demonstration   of  the 
nature  of  scurvy  and  its  relation  to  faulty  diet,  it  was  necessary 
to  employ  another  species  of  animal,  the  guinea  pig,  as  an  ex- 
perimental subject. 

388.  An  Adequate  Diet  May  Be  Remarkably  Simple. — From 
what  has  been  said  it  will  be  appreciated  that  a  .diet  may  be 
remarkably  simple,  viz.:  consist  of  a  single  purified  protein,  a 
source  of  the  sugar  glucose,  nine  mineral  elements  and  two  un- 
characterized  dietary  factors,  and  be  entirely  adequate  for  the 
support  of  growth  and  prolonged  well-being  in  the  rat.    From 
relatively  simple  substances  the  animal  tissues  are  capable  of 
synthesizing  many  compounds  of  extraordinary  complexity.  The 
limitations  of  the  tissues  are,  however,  sharply  defined,  and  if 
the  circulating  fluids  which  constitute  the  environment  of  the 
living  cells,  deviates  appreciably  from  very  definite  composition, 
the  efficiency  of  their  functioning  is  lowered,  and  their  vitality 
affected.    The  degree  to  which  they  are  affected  can  serve  as 


366      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

a  measure  of  the  extent  of  the  departure  of  the  diet  from  the 
optimum,  provided  the  right  kind  of  observations  are  made  to 
bring  this  to  light. 

389.  Great  Stimulus  to  New  Investigation  During  the  Last 
Few  Years. — The  line  of  study  which  was  pursued  by  the  author 
led  to  the  formulation  of  the  above  described  working  hypothesis 
which  has  so  effectively  served  as  a  guide  to  the  interpretation 
of  experimental  data  since  that  time.    This  clear-cut  statement 
of  the  essential  factors  which  the  diet  must  furnish  in  order  to 
maintain  normal  nutrition  served  to  enable  anyone  to  study 
the  dietary  properties  of  any  food  substance  or  mixture,  using 
animals  as  test  organisms,  rather  than  through  the  use  of  chemi- 
cal methods.     The  result  of  this  change  in  the  method  of  attack 
on  nutrition  problems  was  that  there  has  been  more  advance 
in  this  field  since  1915  than  in  many  years  before.    It  made 
possible  the  development  of  the  biological  method  for  the  anal- 
ysis of  a  food-stuff.    This  method  gives  exact  information  as 
to  the  quality  of  every  factor  which  contributes  to  the  success 
of  the  nutrition  of  an  animal.    This  method  has  been  described 
in  Chapter  II,  p.  27.    As  the  result  of  the  accumulation  of  data 
of  this  type  we  have  come  to  look  upon  foods  in  a  new  way. 
Instead  of  classifying  them  on  the  basis  of  their  protein,  or  fat, 
or  carbohydrate  content,  as  was  formerly  done,  we  classify  them 
on  the  basis  of  their  biological  properties  as  foods.    Those  which 
are  faulty  in  similar  respects  are  classed  together,  irrespective 
of  their  chemical   composition.    Thus  the  bean  with   twenty- 
three  per  cent  of  protein,  is  logically  classed  with  the  potato 
which  has  but  two  per  cent,  because  the  bean  proteins  are  of 
very  poor  quality  and  are  of  little  use  for  the  promotion  of 
growth  or  for  the  repair  of  tissue  waste.    The  classification  re- 
ferred to,  however,  was  the  outcome  of  the  discovery  that  all 
vegetable  foods  which  have  the  function  of  storage  organs  (seeds, 
tubers,  fleshy  roots)  have  similar  dietary  properties  and  similar 
deficiencies  regardless  of  their  chemical  composition  as  revealed 
by  the  standard  food  analysis.    The  highly  specialized  muscle 
tissue  falls  in  the  same  class  with  the  cereals  in  respect  to  its 
dietary  properties,  and  differs  very  markedly  from  the  glandular 
organs  just  as  do  the  seeds,  tubers  and  fleshy  roots  from  the 
vegetative  parts  of  the  plants,  the  leaves. 

390.  Vegetable  Foods  Having  Similar  Biological  Functions 
Have  Likewise  Similar  Dietary  Properties. — Since  mixtures  of 
foods  having  similar  deficiencies  cannot  greatly  enhance  each 


NEW  VIEWPOINTS  OF  NUTRITION  367 

other's  values  in  meeting  the  nutritive  needs  of  an  animal,  we 
should  expect,  from  the  properties  of  the  foods  of  the  seed,  tuber, 
fruit,  root  and  muscle  tissue  group,  that  combinations  of  any 
articles  belonging  to  this  class,  should  not  form  a  satisfactory 
food  supply.  Experience  has  now  amply  demonstrated  that 
this  is  the  case.  The  conclusion  is  warranted,  therefore,  that  it 
is  wise  to  select  foods  from  different  groups,  based  upon  their 
nutritive  qualities  in  order  to  properly  balance  the  resulting 
mixture  so  as  to  make  it  near  in  its  constitution,  what  the  animal 
body  needs  for  its  proper  maintenance.  Numerous  feeding  ex- 
periments have  shown  the  wisdom  of  this  plan.  Most  food  sub- 
stances now  in  common  use  do  not  supplement  each  other  in  a 
very  effective  manner.  Milk,  and  the  thin  leaves  of  plants  are 
of  especial  value  for  enhancing  the  dietary  properties  of  nearly 
all  other  foods,  and  they  are  therefore  of  particular  interest  and 
importance.  It  was  for  this  reason  that  I  have  termed  them 
"protective  foods."  In  a  lesser  degree,  eggs  and  the  glandular 
organs  of  animals  serve  this  purpose  of  improving  the  quality 
of  cereals,  tubers,  fruits,  roots  and  of  meats  of  the  muscle  type, 
but  this  improvement  is  incomplete,  because  of  their  lack  of 
sufficient  calcium. 

The  above  statement  regarding  the  inadequacy  of  a  diet  de- 
rived from  seeds,  tubers,  fleshy  roots,  fruits  and  muscle  meats,  is 
made  again  as  in  the  first  edition  of  this  book,  notwithstanding 
the  assertions  of  Steenbock  that  certain  yellow  pigmented  root 
vegetables,  such  as  carrots  and  yellow  turnips,  and  yellow  maize, 
as  contrasted  with  white  or  red  varieties,  are  decidedly  richer  in 
fat-soluble  A.  There  appears  good  reason  to  believe  that  certain 
varieties  of  vegetables  are  superior  to  certain  others  with  respect 
to  their  content  of  fat-soluble  A,  and  apparently  yellow  maize 
represents  a  case  where  the  yellow  pigment  accompanies  the 
superior  nutritive  property.  The  idea  that  the  anti-ophthalmic 
substance  is  related  to,  or  associated  generally  with  the  yellow 
pigments  of  plants  has  been  conclusively  disproved  by  the  work 
of  Palmer  and  his  associates  (4).  But  even  if  the  statement 
is  accepted  that  certain  varieties  of  vegetables  can  serve  as  an 
adequate  source  of  fat-soluble  A,  it  would  not  alter  in  any  way 
the  truth  of  the  generalization  that  diets  containing  yellow  pig- 
mented products  would  not  prove  satisfactory.  The  diets  of 
this  character  would  be  deficient  in  certain  mineral  elements, 
and  sufficiently  so  to  make  it  impossible  to  secure  normal  devel- 
opment in  young  animals.  The  first  of  these  in  importance 


368      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

would  be  calcium,  but  sodium  chlorid  and  phosphorus  would  also 
contribute,  by  their  relative  deficiencies,  to  prevent  the  normal 
nutrition  of  the  animals. 

391.  Early  Nutrition  Investigators  Ignored  Human  Ex- 
perience with  Diets  of  Different  Types. — It  is  remarkable  that 
physiologists  and  others  who  were  interested  in  the  subject  of 
nutrition,  failed  for  so  many  years  to  appreciate  evidence  so 
abundant  in  human  experience,  that  the  proper  selection  of  food 
was  a  most  important  means  of  improving  or  preserving  health. 
Beri-beri  incapacitated  many  millions  of  people  during  the  cen- 
turies before  its  cause  became  known.  It  certainly  occurred  in 
Japan  two  centuries  before  the  Christian  era.  It  was  not,  how- 
ever, until  Eijkman,  in  1897,  compared  the  effects  of  different 
kinds  of  rice  used  as  human  food  in  Java,  on  pigeons  and  poul- 
try, that  a  clue  was  gained  as  to  the  actual  cause  of  the  disease. 

It  had  been  appreciated  for  more  than  a  century  by  some 
people  that  certain  fresh  fruits  and  vegetables  would  effect  a 
cure  of  scurvy,  and  that  it  attacked  only  those  who  were  re- 
stricted for  a  time  to  a  diet  of  stale  or  cooked  foods.  It  was 
not  until  after  1900,  however,  that  Hoist  brought  out  clearly 
through  his  experiments,  on  animals,  the  fact  that  cooked  and 
dried  foods  were  scorbutic  and  that  fresh  vegetables  had  a  most 
extraordinary  power  to  induce  relief  of  the  symptoms  of  scurvy. 
The  nature  of  the  cause  of  scurvy  could  not  be  discovered  by 
experiments  with  the  rat,  since  it  is  not  susceptible  to  this  dis- 
ease. The  guinea  pig  is  especially  well  adapted  for  this  purpose. 

Eye  lesions  varying  from  mild  to  distressing  nature  have  been 
common  in  several  parts  of  the  world  for  many  years.  No  stu- 
dent of  nutrition  suspected  that  there  was  any  cause  for  these 
other  than  infection  until  the  relation  of  one  type  to  specific 
starvation  for  fat-soluble  A  was  established.  McCollum  and 
Simmonds  showed  clearly  that  the  keratomalacia  or  xeroph- 
thalmia  which  had  been  observed  by  several  investigators  who 
had  restricted  rats  to  faulty  diets,  was  due  not  primarily  to  in- 
fection, but  was  of  specific  dietary  origin  and  results  from  lack 
of  fat-soluble  A.  It  is,  therefore,  a  symptom  of  a  deficiency  syn- 
drome comparable  to  beri-beri  or  scurvy.  Human  diets  are 
always  too  complex  to  admit  of  interpretation  as  to  their  defi- 
ciencies except  on  the  basis  of  carefully  planned  experiments  on 
animals.  It  was  for  this  reason  that  it  was  impossible  for  the 
earlier  investigators  to  discover  the  true  causes  of  the  so-called 
deficiency  diseases.  Experimental  studies  with  diets  composed 


NEW  VIEWPOINTS  OF  NUTRITION  369 

of  purified  food  substances  formed  the  key  to  the  complete 
understanding  of  the  natures  of  the  etiological  factors  in  each 
of  these  syndromes.  Perfecting  the  biological  method  for  the 
analysis  of  a  food-stuff,  formed  the  foundation  of  our  knowledge 
of  how  to  combine  our  natural  foods  so  as  to  prepare  diets  which 
fall  little  short  of  the  ideal  in  their  capacity  to  induce  optimal 
nutrition. 

The  rapid  development  in  the  course  of  a  decade,  of  a  satis- 
factory understanding  of  the  fundamental  principles  of  nutrition, 
and  the  manner  in  which  satisfactory  diets  can  be  planned,  con- 
stitutes one  of  the  greatest  triumphs  in  the  whole  field  of  science. 
To-day  the  whole  subject  seems  relatively  simple,  and  the  stu- 
dent of  to-day  is  likely  to  forget  that  but  a  decade  ago,  protein 
content,  fuel  value  and  digestibility  were  the  only  factors  deemed 
of  much  importance  in  the  discussion  of  food. 

392.  Scientific  Nutrition  of  Greater  Value  in  Preventive 
Medicine  Than  in  Cure  of  Disease. — The  researches  in  the  field 
of  nutrition  have  a   greater  value  in  preventive  medicine   in 
relation  to  raising  the  vitality  of  mankind,  with  all  that  this 
implies,  than  they  have  in  the  prevention  of  the  occurrence  of 
the  deficiency  diseases.     This  fact  has  never  been  sufficiently 
appreciated.     In  the  aggregate,  by  far  the  most  important  effect 
of  faulty  nutrition  in  man  is  the  result  of  errors  of  one  kind  or 
another  which  are  not  sufficiently  grave  to  cause  prompt  and 
spectacular  failure.     It  is  the  gradual  operation  of  more  or  less 
constant,   but  unperceived   causes,   rather   than   of   great   and 
marked  exposures  of  an  accidental  nature  which  in  nearly  all 
cases  are  responsible  for  undermining  the  health  of  the  individ- 
ual.   Of  these  causes,  it  now  seems  certain,  the  consumption  of 
an  improperly  constituted  diet  is  one  of  the  most  important. 
It  is  the  cause  of  inferiority  in  physical  development,  instability 
of  the  nervous  system;  lack  of  recuperative  power  and  endurance 
and  consequent  cumulative  fatigue,  and  lack  of  resistance  to 
infections  such  as  tuberculosis  and  other  types  where  specific 
immunity  is  not  easily  developed  by  the  body.     In  addition  to 
these  the  rate  of  development  of  senile  characters  and  conse- 
quently the  length  of  the  span  of  life,  are  greatly  influenced  by 
the  type  of  diet  employed.     It  is  important  for  us  to  inquire 
how  far  such  defective  diets  as  result  from  unwise  selection  of 
ordinary  foods,  can  influence  the  life  history  of  man  and  animals. 

393.  An  Effort  to  Duplicate  Human  Experience  with  Diet 
with  a  Rat  Colony. — Some  years  ago  the  idea  occurred  to  me 


370      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

that  we  had  progressed  sufficiently  far  in  our  investigations  to 
make  it  possible  to  duplicate  human  experience  as  relates  to 
diet,  with  our  colony  of  domestic  rats.  A  systematic  attempt 
has  been  made  to  do  this.  All  factors  other  than  diet,  such  as 
temperature,  ventilation,  illumination,  cleanliness  and  oppor- 
tunity for  exercise,  were  uniform  in  these  experiments.  The  only 
factor  in  the  lives  of  the  animals  comprising  the  different  groups 
which  was  different,  was  the  character  of  the  diet.  Such  varia- 
tions as  were  observed  in  the  physical  development,  fertility, 
capacity  to  produce  milk  of  satisfactory  quality  and  in  suffi- 
cient amount  for  the  nutrition  of  the  young,  length  of  life  and 
age  at  which  the  first  signs  of  senility  appeared,  can  safely  be 
attributed  to  the  character  of  the  diets  employed.  We  had 
available  to  aid  us  in  the  planning  of  the  diets  the  extensive  data 
obtained  in  the  application  of  the  biological  method  for  the 
analysis  of  a  food-stuff.  All  the  more  important  natural  foods 
employed  in  human  nutrition  in  the  north  temperate  zone  had 
been  examined  by  this  method.  In  each  case  we  were  able  to 
state  definitely  the  nature  of  the  fault  or  faults  in  the  diet,  and 
the  extent  to  which  each  departed  from  approximately  the  opti- 
mum in  quality.  These  experiments  afforded  data  which  are  of 
more  than  ordinary  interest  when  we  consider  the  parallel  in 
physical  development,  and  in  such  other  points  of  comparison 
as  can  be  drawn  between  man  and  the  lower  animals. 

394.  Important  to  Secure  Effects  of  Diet  on  Life  History. 
— We  came  to  appreciate  some  years  ago,  that  we  were  able 
to  demonstrate  in  short  experiments  only  faults  of  a  pronounced 
nature.  This  is  what  is  to  be  expected.  If  the  tissues  are  sub- 
jected to  only  slight  deviations  from  the  optimum  in  their  food 
supply,  they  will  not  deteriorate  rapidly  as  they  do  when  the 
faults  in  the  diet  are  more  pronounced.  It  was  to  be  expected, 
however,  that  longer  periods  of  observation  would  reveal  defects 
of  a  lower  order.  This  we  have  found  to  be  the  case.  There  was 
a  time  a  few  years  ago  when  any  investigator  of  a  nutrition  prob- 
lem would  have  said  that  a  diet  which  was  adequate  for  the 
support  of  growth  through  a  considerable  portion  of  the  period 
during  which  growth  normally  takes  place,  would  certainly  be 
adequate  for  the  maintenance  of  health  and  vigor  in  the  adult. 
The  experiments  with  domestic  animals  conducted  at  the  Wis- 
consin Experiment  Station,  clearly  forecasted  the  necessity  of 
including  reproduction  records  as  a  means  of  refining  the  technic 
of  nutrition  studies  so  as  to  make  possible  more  accurate  esti- 


NEW  VIEWPOINTS  OF  NUTRITION  371 

mations  of  quality  in  one  or  more  factors  in  the  diet.  Miss  Sim- 
monds  and  I  have  developed  this  idea  and  have  applied  this 
principle  in  our  work  since  1915.  We  realized  the  importance 
of  attempting  to  answer  the  question:  How  sensitive  is  an  animal 
to  faulty  diets  of  different  types?  Will  not  faults  in  the  diet 
which  are  too  slight  to  affect  the  animal  promptly  during  the 
growing  period  to  an  extent  which  will  be  observable,  become 
easily  apparent  if  they  exert  their  influence  upon  it  at  a  time 
when  it  is  meeting  the  unusual  demand  occasioned  by  pregnancy 
or  the  nursing  of  young?  Will  not  the  growth  and  well-being 
of  the  young  and  the  capacity  of  a  family  to  remain  in  a  state 
of  vigor  during  succeeding  generations  when  confined  to  a  cer- 
tain type  of  diet,  reveal  shades  of  quality  not  to  be  discriminated 
in  a  short  experiment?  We  have  now  tested  these  propositions 
sufficiently  to  enable  us  to  give  very  definite  answers  to  them. 
The  results  have  amply  demonstrated  that  any  fault  in  the  diet, 
however  slight,  which  causes  it  to  deviate  from  the  optimum, 
will,  if  it  exerts  its  influence  over  a  sufficient  period,  surely  be 
reflected  somewhere  in  the  life  history  of  the  individual  or  its 
descendants.  The  sensitiveness  of  the  rat  to  faulty  diets,  which 
fall  but  little  short  of  the  optimum,  is  remarkably  great,  if  such 
diets  are  persisted  in  for  considerable  periods.  In  certain  criti- 
cal conditions  such  as  pregnancy,  such  effects  become  observable 
in  a  short  time.  The  nursing  period  is  almost  equally  critical 
in  that  small  departures  from  the  optimum  composition  of  the 
diet  leave  their  mark  on  the  vitality  of  the  young  and  frequently 
also  on  the  vitality  of  the  mother. 

395.  Impossible  to  State  the  Minimum  Requirement  of  Any 
One  Food  Factor  Unless  All  Dietary  Factors  Are  Evaluated. 
— We  have  reached  the  conclusion  that  it  is  not  possible  to  state 
the  amount  of  any  food  factor  which  constitutes  the  minimum 
or  the  optimum,  or  an  excess,  without  taking  into  consideration 
the  biological  values  of  each  of  the  other  factors  in  the  diet. 
The  minimum  amount  of  any  dietary  factor  of  constant  quality, 
which  will  just  serve  to  maintain  apparently  normal  well-being, 
will  fail  to  suffice  when  another  factor  is  modified  so  as  to  be 
less  satisfactory,  and  after  such  a  modification  of  the  diet,  in- 
creasing either  of  the  two  factors  under  consideration  will  suf- 
fice to  protect  the  body  from  harm  in  some  measure.  There  is 
a  principle  of  relativity  which  is  of  fundamental  importance  in 
estimating  the  value  of  a  diet  as  a  whole.  The  diet  must  be 
considered  as  made  up  of  a  number  of  factors,  and  an  effort 


372      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

made  to  adjust  each  factor  at  the  optimum.  Long  observation 
of  the  type  of  experiments  here  described,  serves  to  reveal  when 
animals  are  brought  into  a  "twilight  zone"  of  nutritional  in- 
stability, but  in  which  there  is  no  external  evidence  that  they  are 
not  in  the  optimum  condition. 

396.  Remarkably  Accurate  Estimations  of  Nutritive  Value 
Are  Possible  by  Animal  Experiments. — The  results  of  observing 
animals  beyond  the  completion  of  growth,  to  determine  their 
fertility,  success  in  rearing  young  and  the  rate  at  which  they 
developed  the  characteristics  of  old  age,  were  so  striking  that 
we  extended  our  observations  to  include  restricting  single  fam- 
ilies to  a  monotonous  diet  through  several  generations.  This 
brought  to  light  the  fact  that  a  diet  may  be  sufficiently  good  to 
enable  an  animal  to  grow  in  a  perfectly  normal  manner,  and  to 
exhibit  a  moderate  amount  of  fertility,  yet  with  each  succeeding 
generation  the  progeny  becomes  smaller  and  less  well  developed 
physically,  and  after  two,  three  or  four  generations  the  strain 
dies  out.  Several  comparable  examples  of  similar  experience 
in  man  may  be  cited.  Campbell  (5)  stated  that  among  the 
poorer  classes  in  the  slums  of  English  cities,  the  family  never 
passes  beyond  the  third  generation.  Galton  (6),  in  a  statis- 
tical analysis  of  one  thousand  town  families  and  one  thousand 
country  families  selected  from  the  town  of  Coventry  and  the 
surrounding  rural  population,  found  that  the  town  population 
supplied  to  the  succeeding  generation  but  three  quarters  of  the 
number  supplied  by  a  similar  number  of  country  people.  In 
two  generations  the  adult  grandchildren  of  the  town  dwellers 
amounted  to  but  little  more  than  half  the  number  of  descendants 
of  the  country  dwellers.  The  employed  urban  dwellers  are  con- 
tinually being  recruited  from  country  stock,  and  themselves 
tend  to  die  out.  Food  is  cheaper  in  rural  districts  and  the  selec- 
tion and  quality  is  distinctly  better  generally  speaking,  than  it 
is  where  the  supply  is  derived  almost  entirely  from  the  grocery 
store.  The  grocer  carries  a  surprising  proportion  of  stock  de- 
rived from  cereal  grains,  legume  seeds,  fruits,  tubers  and  muscle 
meats.  It  has  already  been  emphasized  that  food-stuffs  from 
this  list  cannot  be  combined  so  as  to  constitute  a  satisfactory 
diet.  The  behavior  of  our  rat  population  when  restricted  to 
diets  corresponding  in  their  origin  to  those  of  the  urban  dweller 
of  either  England  or  the  United  States,  will  be  described  im- 
mediately below.  The  extent  to  which  the  rat  has  proven  to  be 
sensitive  to  even  small  modifications  of  the  nature  of  its  diet  is 


NEW  VIEWPOINTS  OF  NUTRITION  373 

truly  amazing.  It  suggests  that  it  is  much  more  important  than 
has  been  hitherto  believed,  to  have  the  diet  nicely  adjusted  with 
respect  to  all  its  essential  constituents,  in  order  that  the  develop- 
ment shall  be  as  nearly  the  optimum  as  possible.  It  is  under 
such  conditions  that  the  characteristics  of  youth  are  preserved 
as  long  as  possible,  and  the  span  of  life  prolonged. 

397.  A  Specific  Illustration  of  the  Effects  of  Faulty  Nutri- 
tion.— As  an  illustration  of  the  extent  to  which  we  can  control 
the  life  history  of  a  group  of  experimental  animals,  we  may  take 
the  effects  of  a  diet  consisting  of  degerminated  cereal  products 
such  as  bolted  wheat  flour,  degerminated  corn  meal  and  polished 
rice,  whole  wheat,  maize  meal,  rolled  oats,  potatoes,  peas  and 
beans.  Irrespective  of  the  proportions  in  which  the  foods  listed 
are  combined,  the  resulting  mixture  will  contain  proteins  of  rela- 
tively poor  quality.  Its  content  of  calcium,  phosphorus,  sodium 
and  chlorin  will  be  decidedly  below  the  optimum.  It  would  be 
very  deficient  in  the  organic  factor,  fat-soluble  A.  The  larger 
the  proportion  of  milled  products  introduced,  the  greater  will  be 
each  of  the  deficiencies  enumerated.  In  order  to  make  our  illus- 
tration as  striking  as  possible,  let  us  take  a  mixture  consisting 
to  the  extent  of  about  50  per  cent  of  degerminated  wheat,  maize 
and  rice  products,  the  remainder  being  derived  from  the  entire 
cereal  grains  and  legume  seeds. 

On  such  a  food  supply  young  rats  would  fail  to  grow.  They 
would  develop  deformities  which  are  characteristic,  the  body 
being  too  short  and  stocky,  and  the  thorax  more  or  less  collapsed, 
and  misshapen.  Their  lives  would  be  measured  by  a  very  few 
months  at  greatest. 

With  the  same  basal  mixture,  supplemented  with  small 
amounts  of  butter  fat  to  furnish  fat-soluble  A,  and  the  mineral 
elements  in  which  the  food  is  deficient,  in  amounts  so  small  as 
to  only  partially  correct  the  deficiencies  of  the  diet,  we  could 
easily,  from  experience,  adjust  these  corrective  additions  so  as 
to  enable  us  to  predict  that  the  group  of  young  rats  fed  this 
second  diet,  would  grow  at  about  half  to  two-thirds  the  normal 
rate  to  something  like  two-thirds  the  normal  adult  size,  after 
which  they  would  remain  stunted.  Within  a  few  weeks  after 
the  cessation  of  growth,  the  animals  would  show  distinct  signs 
of  poor  nutritive  condition.  Their  hair  would  be  harsh  and 
rough.  The  animals  would  lose  the  normal  solicitude  about 
grooming  themselves,  and  would  become  unclean  looking.  They 
would  never  have  any  young,  but  would  steadily  deteriorate  and 


374      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

die  at  a  very  early  age,  about  six  or  seven  months.  (See  Chart  11.) 

398.  Effects  of  Diet  in  Determining  the  Span  of  Life. — The 
extreme  span  of  life  of  the  rat  under  highly  satisfactory  condi- 
tions of  nutrition  and  hygienic  surroundings  is  about  thirty-six 
months.     Probably  two-thirds  of  all  animals  kept  under  the 
best  laboratory  conditions  would  die  before  reaching  the  age  of 
two  years.     In  the  group  of  animals  just  described,  therefore,  the 
span  of  life  was  reduced  to  about  one-fourth  to  one-sixth  of  its 
extreme  limit,  as  the  result  of  faulty  nutrition  caused  by  a  diet 
in  which  no  essential  was  entirely  lacking,  or  lacking  to  a  degree 
which   would   cause  the   development   of   a   specific   deficiency 
disease. 

Employing  other  portions  of  the  basal  food  mixture  described, 
and  in  preparing  these  portions  for  feeding  a  series  of  experi- 
mental groups  of  young  rats,  we  could,  in  the  light  of  our  experi- 
ence, add  such  amounts  of  a  growth-promoting  fat,  and  of  the 
several  mineral  elements  in  which  the  food  is  deficient,  as  to 
form  a  series  of  diets  which  would  be  progressively  nearer  and 
nearer  to  the  optimum  in  the  character  of  each  of  the  essentials 
for  optimum  nutrition.  When  several  groups  of  young  rats 
were  confined  to  these  diets  we  could  confidently  predict  that 
they  would  differentiate,  one  group  from  another,  in  their  length 
of  life.  All  would  be  able  to  grow  to  the  full  adult  size,  and 
while  they  were  growing  they  would  appear  to  be  perfectly  nor- 
mal animals  with  bright  eyes  and  glossy  coats.  The  interval 
following  the  completion  of  growth  and  preceding  rapid  decline 
would  be  determined  by  the  extent  to  which,  in  any  single  case 
the  faults  in  the  food  mixture  were  corrected  by  suitable  addi- 
tions. Thus  we  could  make  them  last  six  months,  ten  months 
or  twenty  months  after  they  ceased  to  grow  before  they  would 
appear  old  and  rough  looking  and  would  show  the  irritability 
characteristic  of  most  old  rats. 

399.  Fertility  and  Infant  Mortality  Are  Valuable  Indexes 
to  the  State  of  Nutritive  Well-Being. — In  the  case  of  those 
groups  where  the  state  of  their  nutrition  was  sufficiently  good  to 
enable  them  to  show  a  moderate  fertility,  it  would  be  observed 
that  the  infant  mortality  would  be  higher  the  more  deficient  the 
food  mixture.     On  such  diets  partly  corrected  by  suitable  addi- 
tions   the    infant    death    rate    has    been    uniformly    100    per 
cent.    Another  group  with  additions  more  nearly  approaching 
the  optimum  will  rear  40  to  60  per  cent  of  their  young,  while 
the  same  basal  mixture,  fed  supplemented  with  the  right  amounts 


375 


376      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

of  the  substances  in  which  it  is  deficient  will  produce  a  group 
of  adult  rats  which  will  scarcely  lose  one  litter  in  a  hundred. 

Formerly  in  our  colony  the  terminal  event  in  the  lives  of  many 
of  the  animals  restricted  to  such  deficient  diets  as  have  just  been 
described,  was  a  lung  infection  caused  by  streptothrix.  As  the 
animals  lost  their  vitality  through  restriction  to  faulty  diets  they 
became  more  and  more  a  prey  to  the  disease.  With  selection 
of  vigorous  breeding  animals  and  with  cleanliness  we  have  suc- 
ceeded in  greatly  reducing  the  occurrence  of  this  infection. 

When  the  diet  is  made  sufficiently  good  to  enable  the  rats  to 
rear  only  a  fair  amount  of  their  young,  there  is  a  strong  tendency 
for  the  animals  to  be  smaller  with  each  succeeding  generation, 
until  within  three,  four  or  five  generations  they  fail  to  reproduce 
and  the  strain  dies  out.  All  the  experimental  groups  described, 
it  should  be  remembered,  would  have  been  sufficiently  well  nour- 
ished to  enable  them  to  grow  to  two-thirds  to  full  adult  size, 
and  to  appear  normally  nourished  while  they  were  growing,  yet 
dietary  deficiencies  of  no  greater  magnitude  than  those  we  are 
here  discussing,  may  profoundly  influence  the  life  history  of 
the  individual  or  the  history  of  the  family. 

Using  the  degerminated  cereal,  and  whole  cereal,  and  legume 
seed  mixture  described  as  the  basis  of  the  experimental  diets  just 
discussed,  it  would  be  necessary  to  add  about  1.5  per  cent  of 
calcium  carbonate;  1.0  per  cent  of  sodium  chlorid;  perhaps 
enough  of  some  phosphate  to  furnish  about  half  of  one  per  cent 
of  the  phosphate  radical,  to  make  the  diet  complete  with  respect 
to  its  mineral  content.  The  addition  of  3  to  5  per  cent  of 
butter  fat  or  2.0  per  cent  cod  liver  oil,  and  15  per  cent  of  a 
purified  protein,  casein  for  example,  would  complete  the  organic 
portion  of  the  ration  and  would  constitute  a  highly  satisfactory 
food  mixture  through  many  generations  with  no  noticeable 
deterioration  of  the  race  on  account  of  monotony  of  food  supply. 
How  strikingly  similar  is  the  history  of  such  a  series  of  animals 
on  carefully  graded  diets,  to  the  experience  of  the  urban  dwellers 
of  England,  which  Galton  describes.  (See  Chart  12.) 

400.  One  May  Have  a  Surprising  Variety  of  Food  and  Still 
Have  a  Faulty  Diet. — The  most  surprising  generalization  which 
is  warranted  by  exact  nutrition  studies,  is  that  even  a  diet  com- 
posed of  cereal  grains,  legume  seeds,  tubers,  fleshy  roots,  fruits 
and  muscle  cuts  of  meat,  irrespective  of  the  proportions  in  which 
the  components  are  represented,  the  variety  which  it  affords,  or 
the  chemical  composition  as  shown  by  even  the  most  searching 


377 


378      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

analysis  by  chemical  methods,  will  fail  to  support  satisfactory 
growth  in  a  young  rat.  It  will  further  fail  to  maintain  satis- 
factory health  and  vitality  in  an  adult  which  has  been  reared  on 
a  diet  which  is  of  high  quality  until  it  has  completed  its  growth, 
and  is  later  transferred  to  its  experimental  diet.  Such  a  diet 
may  contain  any  or  all  of  a  list  of  foods  including  wheat,  maize, 
rolled  oats,  barley,  rye,  pea,  bean,  soy  bean,  potato,  turnip,  rad- 
ish, beet,  steak,  ham,  roast,  etc.,  or  any  other  seed,  tuber,  root, 
and  muscle  meat,  and  still  fail  signally  to  maintain  the  vitality 
of  a  rat.  Muscle  meats,  as  has  already  been  stated,  enhance 
such  a  mixture  only  with  respect  to  protein  and  phosphorus, 
among  the  factors  in  which  it  is  deficient.  When  such  meats 
are  included  in  the  above  list,  the  deficiencies  of  the  diet  will  be 
limited  to  calcium,  sodium,  chlorin  and  fat-soluble  A.  In  the 
above  discussion  we  have  limited  ourselves  to  the  nutrition  of 
the  rat.  This  species,  as  has  already  been  pointed  out,  does  not 
require  the  anti-scorbutic  substance  in  its  diet.  In  order  to 
make  such  a  food  supply  as  we  are  now  discussing,  complete 
for  human  nutrition,  it  would  be  necessary  to  include  a  certain 
part  of  the  fruit  in  the  raw  condition.  Raw  potato  and  other 
root  vegetables  would  also  serve  this  purpose  well,  whereas  the 
seeds  of  the  cereals  or  legumes,  or  muscle  meats,  are  of  very  little 
value  for  this  purpose. 

401.  Any  Diet  Which  Is  Unsuited  for  the  Promotion  of 
Growth  in  the  Young  Will  Not  Be  Satisfactory  for  the  Main- 
tenance of  Health  in  the  Adult. — The  question  naturally  arises 
in  the  mind  as  to  whether  a  diet  may  be  satisfactory  for  the 
maintenance  of  optimal  nutrition  in  the  adult,  but  unsuited  to  the 
nutritive  needs  of  the  young.  We  have  sought  to  gain  an  answer 
to  this  question.  By  restricting  youthful  adult  animals  to  diets 
which  were  known  to  be  incapable  of  supporting  growth  in  the 
young,  we  have  convinced  ourselves  that  there  is  no  important 
difference  in  the  nutritive  requirements  of  the  young  and  the 
adult.  Any  diets  which  we  have  studied,  which  were  not  satis- 
factory for  the  promotion  of  growth  in  a  young  rat,  were  found 
to  cause  some  damage  to  adults  which  were  restricted  to  them. 
This  might  be  manifested  in  early  aging,  short  life,  lowered  fer- 
tility or  the  deterioration  of  a  family  restricted  to  it  through 
several  generations.  We  are  of  the  opinion,  therefore,  that  any 
diet  which  is  not  suited  for  the  promotion  of  optimum  nutrition 
during  growth  will  fail  to  support  an  animal  so  as  to  induce  a 
long  span  of  life,  and  sustain  the  optimal  well-being  over  a  long 
period. 


NEW  VIEWPOINTS  OF  NUTRITION  379 

402.  Effects  of  Faulty  Nutrition  on  the  Attitude  of  the 
Mother   Toward   Her   Young. — The   reaction   of  mother  rats 
toward  their  young,  when  confined  to  certain  types  of  faulty 
diets,  especially  those  low  in  protein,  is  especially  interesting. 
In  many  such  cases  the  mothers  react  abnormally  toward  their 
young  and  destroy  them  soon  after  birth.    The  normally  nour- 
ished rat  practically  never  destroys  her  young,  but  is  on  the 
contrary,   very    solicitous    for   their   welfare.    We   have  taken 
mothers  which  have  destroyed  two  or  three  litters,  and  changed 
their  diet  for  the  better,  and  have  seen  them  thereafter  produce 
other  young  and  care  for  them  in  the  normal  manner.    Miss 
Simmonds  and  I  are  inclined  to  regard  this  as  especially  signifi- 
cant.   It  involves  breaking  down  one  of  the  most  fundamental 
attributes  of  the  nervous  system,  viz.:   the  maternal  instinct, 
and  the  development  of  infanticidal  tendencies,  through  disturb- 
ance of  the  proper  balance  between  certain  factors  in  the  diet. 

403.  A  Poorly  Nourished  Population  Tends  to  Be  the  Prod- 
uct of  Individuals  Young  in  Years. — Many  animals  on  diets 
which  are  faulty  in  some  degree,  show  reduced  fertility  or  even 
remain   sterile.    When   the   fertility    is   greatly   reduced   it   is 
usually  the  case  that  any  young  which  are  born  are  produced 
while  the  mothers  are  still  young.    When  fertility  is  low  the 
litters  tend  to  be  smaller  than  normal,  and  as  a  rule,  although 
not  invariably,  the  intervals  between  litters  is  abnormally  long. 
Sterility  may  be  independent  of  physical  vigor,  so  far  as  the 
condition  of  the  animals  can  be  judged,  and  may  exist  in  spite 
of  sexual  activity  in  the  female.    We  have  frequently  observed 
in  male  rats  which  were  rendered  prematurely  old  as  the  result 
of  deficient  diet,  atrophy  of  the  testes.     Osborne  and  Mendel  (7) 
have  made  similar  observations  on  rats  fed  liberally  with  yeast. 
Although  not  invariably  true,  one  may  say  that  in  general,  the 
adherence  to  a  diet  which  is  much  below  the  optimum  in  quality 
with  respect  to  one  or  more  factors,  restricts  fertility  to  early 
life,  and  leads  to  the  perpetuation  of  the  species  by  individuals 
which  are  chronologically  young,  although  they  may  be  con- 
siderably advanced  in  respect  to  physiological  deterioration. 

404.  The   Poorly  Nourished  Individual   Tends  to   Hurry 
Through  His  Span  of  Life. — We  interpret  the  observations  we 
have  made  on  the  influence  of  monotonous  diets  falling  below 
the  optimum  in  quality,  and  failing,  therefore,  to  maintain  satis- 
factory nutrition  over  a  prolonged  period,  to  mean  that  when 
the  diet  is  faulty  the  individual,  in  effect,  tends  to  hurry  through 
its  life  history,  and  each  phase  of  its  history  is  shortened.    The 


380      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

tissues  seem  to  suffer  loss  of  efficiency  at  a  greatly  accelerated 
rate.  Youthful  characteristics  quickly  disappear,  the  termina- 
tion of  the  period  of  fertility  is  early  reached,  and  signs  of  sen- 
ility such  as  thinness  of  hair,  lack  of  luster  of  the  hair,  changes 
in  the  texture  of  the  skin,  and  instability  of  the  nervous  system 
appear. 

405.  A  Striking  Parallel  Between  Human  Experience  and 
the  History  of  our  Animals  on  Similar  Diets. — There  is  per- 
haps nothing  more  worthy  of  careful  consideration  as  a  human 
problem  than  the  suggestive  results  of  the  behavior  of  our  ex- 
perimental rats  as  modified  by  diet.    They  have  varied  from 
the  most  highly  satisfactory  type  for  the  promotion  of  growth, 
fertility  and  the  preservation  of  vigor,  to  the  opposite  extreme 
when  little  or  no  growth  could  take  place  and  physical  deteriora- 
tion developed  apace  leading  to  early  death.    The  well  nour- 
ished rat  is  large  and  muscular  and  has  a  glossy  coat,  bright 
eyes  and  a  quiet  disposition.    When  placed  in  new  surroundings 
it  shows  a  strong  desire  to  explore  its  environment.    As  soon  as 
this  is  done  it  settles  down  to  rest,  and  at  no  time,  so  long  as 
it  remains  on  familiar  ground,  does  it  manifest  much  activity. 
Its  nervous  system  is  stable  and  its  threshold  of  stimulus  rela- 
tively high.     It  is  not  apprehensive  of  danger  and   does  not 
manifest  much   curiosity   as  to   its   surroundings   except  when 
placed  upon  new  territory.     Such  a  rat  may  be  handled  several 
times  a  week  by  lifting  it  by  the  tail  by  means  of  tongs,  which 
causes  some  discomfort,  yet  it  will  fail  to  remember  the  experi- 
ence or  develop  as  a  result  fear  or  resentment  at  being  handled 
in  the  same  manner  or  with  the  unprotected  hand.    A  cage  con- 
taining half  a  dozen  such  animals  can  be  opened  without  caus- 
ing them  to  rise  from  a  resting  posture,  and  one  can  reach  in 
with  a  bare  hand  and  take  them  by  the  tails,  pulling  them  about 
so  as  to  collect  the  entire  group  in  one  hand,  and  can  withdraw 
them  as  a  single  handful  and^demonstrate  them  to  a  visitor  with 
their  heads  down  for  several  seconds  without  causing  them  any 
alarm.    They  do  not  resent  being  handled,  even  being  held  sus- 
pended with  their  heads  down,  although  this  causes  them  some 
discomfort,  and  they  do  not  attempt  to  bite. 

406.  Nervousness  of  Animals  on  Certain  Types  of  Faulty 
Diets. — On  the  other  hand,  when  the  diet  is  faulty  in  certain 
respects,  the  nervous   system   is   profoundly   affected.     This   is 
perhaps  most  pronounced  with  diets  deficient  in  calcium  or  in 
phosphorus.    Inadequacy  of  the  protein  of  the  diet  is  also  capa- 


NEW  VIEWPOINTS  OF  NUTRITION  381 

ble  of  causing  irritability  and  nervousness.  We  have  observed  a 
group  of  rats  which  had  been  restricted  during  growth,  to  a  diet 
in  which  the  sole  protein  content  was  6  per  cent,  half  of  which 
was  derived  from  maize  and  half  from  peas.  They  were  very 
apprehensive  of  danger  and  would  retire  in  alarm  when  the  cage 
was  opened.  Well  nourished  animals  do  not  become  alarmed 
under  such  conditions. 

In  extreme  cases,  young  rats  which  are  restricted  for  a  few 
weeks  to  such  deficient  diets  become  extremely  nervous  and 
irritable.  When  the  cage  is  opened  they  may  retreat  as  far  as 
possible  and  sit  upon  their  haunches  or  crouch  in  an  attitude  be- 
traying great  alarm,  and  squeal  when  an  attempt  is  made  to 
pick  them  up  with  tongs.  One  would  certainly  be  bitten  if  one 
were  so  rash  as  to  attempt  to  take  them  in  the  bare  hands.  It 
is  often  difficult  to  seize  them  by  a  foot  or  by  the  tail  by  means 
of  tongs  because  of  their  frantic  springing  about.  They  even 
leap  out  of  the  cage  past  their  would-be  captors.  Normally 
nourished  rats  can  be  placed  in  a  box  together  and  transported 
to  the  balance  for  weighing,  without  arousing  any  excitement. 
When  the  box  is  temporarily  uncovered  they  do  not  evince  a 
desire  to  escape.  The  nervous  ones,  made  timid  by  faulty  nutri- 
tion, under  these  circumstances  jump  about  frantically  and  make 
violent  efforts  to  escape  the  instant  that  a  ray  of  light  is  ad- 
mitted to  the  box.  Not  infrequently  we  have  corrected  the  diets 
of  animals  in  this  condition  of  nervous  instability  and  have  been 
able  within  three  or  four  weeks,  to  pick  up  the  entire  group  of 
five  or  six  with  one  bare  hand  without  causing  them  any  unrest. 

There  are  in  our  experience  all  gradations  of  nervous  in- 
stability between  these  extremes.  Some  behave  so  as  to  cause 
an  entry  in  the  note-book  that  they  are  "wild,"  but  never  reach 
an  extreme  degree  of  timidity.  Many  times  we  have  observed 
young  rats  nourished  by  mothers  whose  diets  were  deficient  in 
calcium,  to  develop  typical  symptoms  of  tetany.  They  would 
appear  to  be  well  nourished  up  to  the  seventeenth  or  eighteenth 
day  of  nursing,  then  would  suddenly  develop  a  paroxysm. 
These  seizures  were  experienced  at  intervals  for  some  hours 
when  death  resulted.  Timidity  and  nervousness  are  also  char- 
acteristic of  many  rats  whose  diets  are  deficient  in  the  anti- 
neuritic  substance. 

407.  Tetanic  Seizures  in  Young,  Nursing  Mothers  Whose 
Diets  Are  Faulty  in  Certain  Ways. — In  this  connection  mention 
should  be  made  of  the  frequent  destruction  of  young  rats  by 


382     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

their  mothers.  There  are  two  general  causes  of  infant  mor- 
tality in  our  colony.  In  one  case  the  mother  reacts  normally 
toward  her  young  and  makes  an  effort  to  nurse  them,  but  fails 
to  do  so  successfully  because  of  errors  in  her  diet  which  prevent 
the  secretion  of  milk  of  a  normal  character.  Under  such  con- 
ditions the  young  may  grow  for  a  time,  then  become  stunted  and 
require  a  much  longer  period  of  dependence  upon  the  mother 
than  is  usual,  but  finally  reaching  a  state  of  maturity  where 
they  are  capable  of  subsisting  on  the  diet  of  the  mother.  Again 
under  other  experimental  conditions,  especially  when  the  diet  of 
the  mother  is  deficient  in  calcium,  the  young  may  grow  in  a 
manner  essentially  normal  until  the  fifteenth  to  the  eighteenth 
day,  or  thereabouts,  and  then  develop  tetanic  spasms,  strikingly 
suggestive  of  tetany  in  infants.  A  pathological  state  different 
from  that  just  described,  but  characterized  by  great  excitement, 
and  seizures  in  which  the  young  sit  up  on  the  haunches  and 
squeal  violently,  is  frequently  seen  in  little  rats  which  are  nurs- 
ing mothers  whose  diets  are  deficient  in  water-soluble  B,  and 
appears  to  simulate  infantile  beri-beri.  Once  little  rats  are 
observed  to  have  attacks  of  the  kinds  described,  they  usually 
die  within  a  day  or  two. 

408.  Infanticidal  Tendencies  in  Nursing  Mothers  Caused 
by  Faulty  Diet. — In  another  class  is  to  be  placed  the  mother 
rats  which  destroy  their  young  within  a  day  or  two  after  birth. 
This,  we  have  found  to  be  the  rule  in  animals  which  are  re- 
stricted to  diets  in  which  the  protein  moiety  is  inadequate,  espe- 
cially when  it  is  of  rather  poor  quality  and  constitutes  but  a 
small  percentage  of  the  food  mixture.    This  tendency  to  infan- 
ticide may  be,  therefore,  the  specific  result  of  semi-starvation  for 
amino-acids.    The  nature  of  the  lesions  which  develop  in  young 
rats  which  are  suckled  by  mothers  on  faulty  diets  of  the  char- 
acters described  above  have  not  been  sufficiently  studied  to  war- 
rant any  detailed  discussion  of  them. 

409.  Changes  in  Our  Basis  of  Judgment  Regarding  Criteria 
of  Quality  in  Diet. — The  foregoing  account  of  the  changes  in 
the  viewpoint  with  which  we  have  come  to  regard  nutrition  and 
the  interpretation  of  its  problems,  shows  clearly  the  physiologi- 
cal necessity  for  a  proper  balancing  of  the  diet  in  a  sense  dif- 
ferent from  that  in  which  the  term  balanced  was  employed  in 
former  years.    Then  it  was  used  to  express  the  ratio  between 
the  protein  and  other  energy  yielding  constituents  of  the  food 
mixture.    Now  it  includes  fine  adjustments  in  the  relative  pro- 


NEW  VIEWPOINTS  OF  NUTRITION  383 

portions  in  which  the  products  of  protein  digestion  are  furnished 
by  the  diet,  the  concentrations  of  the  several  inorganic  elements 
which  it  contains,  and  the  abundance  which  it  affords  of  the 
essential  vitamins. 

410.  The  Diet  Should  Be  as  Near  the  Optimum  as  Possible 
with  Respect  to  Every  Factor. — The  object  of  this  account  of 
the  effects  of  faulty  diets  which  fall  short  of  meeting  the  nutri- 
tive needs  of  the  body  only  to  minor  degrees,  and  in  many  cases 
in  respect  to  factors  which  are  not  primarily  concerned  with  the 
production  of  the  "deficiency"  diseases,  is  to  emphasize  the  im- 
portance of  taking  regularly,  a  diet  which  approximates  closely 
the  optimum  with  respect  to  every  component.    Whenever  a  diet, 
which  deviates  much  from  the  optimum  in  its  constitution  with 
respect  to  any  of  its  parts,  is  adhered  to  for  any  considerable 
period,  it  leaves  its  mark  upon  the  organism,  and  causes  its 
deterioration  at  a  rate  faster  than  would  result  under  more  favor- 
able conditions. 

411.  Optimal  Physical  Development  and  the  Prevention  of 
Illness,  the  Present- Day  Objective. — Until  recently  the  medical 
profession  was  interested  exclusively  in  the  sick.    The  well  baby, 
the  well  child  or  the  well  adult,  were  entirely  neglected.    Now 
the  idea  is  gaining  ground  that  it  is  more  important  to  keep  a 
person  well  than  to  cure  an  illness  after  it  has  developed.    This 
is  the  great  ideal  of  preventive  medicine.    But  just  as  in  the  past 
the  baby  was  regarded  as  well  until  midnight  wails,  prostration, 
or  a  terrifying  rash  or  eruption  made  attention  to  its  condition 
imperative,  so  to-day  physicians,  health  officials  and  the  public 
itself,  are  in  great  measure  ignoring  all  except  the  most  spec- 
tacular and  compelling  alarms  in  health  matters.    Epidemics 
have  forced  the  chlorination  of  water  supplies  and  the  enforce- 
ment of  quarantine.    The  effects  of  unwise  selection  of  food 
can  confidently  be  asserted  to  exercise  a  greater  debilitating 
effect  upon  an  individual  than  does  in  many  cases  an  attack  of 
an  acute  infection  in  a  well  nourished  one.    Yet  the  effects  of 
faulty  nutrition  exhibited  by  more  than  half  the  people  around 
us  attract  little  or  no  attention. 

412.  Possibilities  of  Scientific  Nutrition  Not  Generally  Ap- 
preciated.— We  hear  much  of  clinics  for  the  removal  of  diseased 
tonsils  and  adenoids,  and  for  the  repair  of  defective  teeth,  but 
almost  nothing  of  a  fundamental  nature  about  the  adoption  of 
habits  of  living  which  would  in  great  measure  exempt  the  next 
generation  from  these  physical  burdens.    Partial  physiological 


384     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

exhaustion  as  exemplified  in  chronic  constipation,  hypersensitive- 
ness  of  the  nervous  system,  diabetes  and  kidney  lesions  has  be- 
come so  common  that  they  attract  little  attention  except  from 
the  patient  and  his  physician,  yet  there  is  much  reason  for  be- 
lief that  a  more  rational  system  of  living,  prominent  in  which 
would  be  a  wise  choice  of  foods,  would  in  great  measure  cause 
the  disappearance  of  these  debilitating  conditions. 

The  trouble  seems  to  be  that  we  are  still  retaining  habits  of 
thought  which  must  sooner  or  later  become  antiquated.  Case 
reports,  autopsies  and  histological  studies  still  focus  our  attention 
upon  the  nature  of  the  lesion,  its  accurate  description,  and  its 
differentiation  from  other  conditions.  Bacteriological  studies 
and  the  triumphs  of  the  serologist  in  immunization  against  in- 
fectious disease,  hold  most  of  our  attention,  while  the  physiology 
of  normal  conditions,  receives  but  little  consideration.  Without 
minimizing  the  importance  of  pathology,  bacteriology  and 
parasitology  in  contributing  to  human  health  and  comfort,  it 
may  well  be  asserted  that  the  time  has  arrived  when  greater  at- 
tention should  be  given  to  the  most  fundamental  problem  of  all, 
viz.:  the  supervision  of  the  conditions  under  which  the  normal 
development  of  the  individual  takes  place.  An  effort  must  be 
made  to  perfect  the  environment  so  as  to  make  the  many  struc- 
tures of  the  body  function  in  a  manner  which  approximates  the 
physiological  ideal.  Such  an  attitude  toward  health  matters 
would  necessitate  the  recognition  as  of  paramount  importance  for 
the  realization  of  its  aims,  the  optimal  regulation  of  the  chemical 
medium  by  which  the  tissues  grow  and  are  sustained.  Technical 
studies  have  brought  to  light  what  casual  inspection  failed  to  dis- 
cern, that  our  most  effective  defensive  barriers  against  most  of 
the  dangers  to  which  our  environment  exposes  us  lie  within  us. 
Perfection  of  physiological  development,  and  the  preservation 
unimpaired  of  the  functions  of  the  organs  and  tissues  of  the  body 
assure,  in  great  measure,  immunity  against  the  painful  effects 
of  certain  diseased  conditions.  Among  all  the  hygienic  factors 
which  influence  the  welfare  of  human  beings  or  the  lower  animals, 
the  nutritional  factor  stands  first  in  importance.  It  is  hoped 
that  the  illustrations  presented  of  the  manner  in  which  the  diet 
may  be  selected  so  as  to  form  a  great  bulwark  in  the  protection 
of  vitality  are  sufficiently  convincing  to  lead  to  a  better  appre- 
ciation of  this  much  neglected  agency  for  the  promotion  of 
health. 


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NEW  VIEWPOINTS  OF  NUTRITION  385 

BIBLIOGRAPHY 

1.  Wells,  H.  G.:     Cited  by  Blunt,  K.  and  Wang,  C.  C.:     The  present 

status  of  vitamines,  Jour,  of  Home  Econ.,  1921,  xiii,  98. 

2.  McCollum,  E.  V.:     Nuclein  synthesis  in  the  animal  body,  Amer.  Jour. 

of  Physiol.,  1909,  xxv,  120. 

3.  Hopkins,  F.  G.:     Feeding  experiments  illustrating  the  importance  of 

accessory  factors  in  normal  dietaries,  Jour,  of  Physiol.,  1912,  xliv,  425. 

4.  Palmer,  L.  S.,  and  Kennedy,  C.:    The  relation  of  the  plant  carotinoids 

to  growth  and  reproduction  in  the  rat,  Jour.  Biol.  Chem.,   1921, 
xlvi,  559. 

5.  Campbell,  H.:    The  causation  of  disease,  London,  1889. 

6.  Galton,   D.:     Healthy  dwellings,   London.    Cited   by   Russell,   R.,   in 

Strength  and  Diet,  New  York,  1906,  p.  32. 

7.  Osborne,  T.  B.,  and   Mendel,  L.  B.:     The  nutritive  value  of  yeast 

protein,  Jour.  Biol.  Chem.,  1919,  xxxviii,  223. 


CHAPTER  XVII 

THE  DIETARY  HABITS  OF  MAN  IN  SEVERAL  PARTS 
OF  THE  WORLD 

413.  The  Polyphemic  Eye  of  the  Faddist  in  Diet. — From 
what  has  been  said  in  earlier  chapters  it  will  be  readily  under- 
stood that  students  of  nutrition  during  any  period  previous  to 
the  last  five  or  six  years  must  necessarily  have  had  an  inadequate 
understanding  of  the  fundamental  principles  which  underlie  the 
science,  and  hence  were  unable  to  interpret  correctly  their  ob- 
servations.   Several  writers  were  inspired  with  enthusiasm  for 
a  special  type  of  diet  and  each  had,  therefore,  a  polyphemic  eye 
for  one  or  another  nutrient  principle  as  overshadowing  others 
in  importance.    Thus  Crichton-Browne  (1)  had  the  conviction 
that  meat  eating  promotes  not  only  physical  vigor,  but  is  re- 
sponsible for  many  other  manly  attributes  as  well.     Chittenden 
(2)  was  an  earnest  supporter  of  the  theory  that  a  low  protein 
dietary  best  promoted  physical  and  mental  well-being,  while 
McKay  (3)  was  led  by  his  observations  on  the  peoples  of  India, 
to  the  conclusion  that  a  liberal  supply  of  protein  in  the  food  of 
man  was  a  factor  of  great  importance  in  determining  the  success 
of  the  human  dietary.     It  is  now  apparent  that  the  protein 
moiety  is  but  one  of  several  indispensable  components  of  an  ade- 
quate food  mixture,  all  of  which  are  indispensable  and  must  be 
viewed  as  of  approximately  equal  importance.    For  each  of  these 
components  there  is  an  optimum,  either  of  amount  or  constitu- 
tion, which  will  best  meet  the  nutritive  needs  of  a  mammal. 
We  are  now  in  a  position  to  reexamine,  with  a  broader  viewpoint 
than  the  earlier  investigators,  the  whole  subject  of  human  nutri- 
tion in  the  light  of  the  results  of  animal  experimentation,  with 
the  prospect  of  arriving  at  a  decision  as  to  the  best  type  or  types 
of  diets  suited  to  the  development  of  an  imperial  race. 

414.  The  Keynote  to  Successful  Nutrition  Is  the  Proper 
Selection  of  Food. — It  has  been  shown  what  chemical  constitu- 
ents form  a  satisfactory  diet  for  a  mammal  and  the  experimental 
evidence  upon  which  the  accepted  views  rest  has  been  described. 

386 


THE  DIETARY  HABITS  OF  MAN  387 

The  dietary  properties  of  each  of  our  more  important  agricul- 
tural products  and  of  each  of  the  animal  products  serving  as  food 
for  man  have  been  pointed  out.  Emphasis  has  been  laid  upon 
the  manner  and  extent  to  which  foods  which  are,  individually 
deficient  in  one  or  more  respects  tend,  when  combined,  to  correct 
each  other's  deficiencies.  The  evidence  is  overwhelming  that  the 
keynote  to  successful  nutrition  is  the  selection  of  foods  having 
unlike  dietary  properties,  but  so  constituted  as  to  supplement 
each  other's  deficiencies  and  to  make  a  mixture  which  affords  the 
most  satisfactory  amounts  of  each  of  the  essential  food  ele- 
ments, rightly  combined.  The  generalization  has  been  made 
that  a  diet  may  afford  a  surprisingly  great  variety  of  food-stuffs, 
including  cereal  grains,  tubers,  fleshy  roots,  fruits,  and  liberal 
additions  of  muscle  meats,  and  still  fall  far  short  of  being  ade- 
quate for  the  support  of  growth  or  for  the  maintenance  of  health 
in  the  adult.  In  the  present  chapter,  the  types  of  diets  which 
are  successful  in  a  rather  high  degree  will  be  described,  and  their 
effects  on  man  and  animals  will  be  illustrated.  At  the  same  time 
the  errors  in  the  selection  of  food  which  mark  the  habits  of  a 
number  of  groups  of  people  in  different  parts  of  the  world,  will 
be  pointed  out. 

415.  Observations  which  Became  the  Basis  of  Important 
Deductions. — The  facts  brought  out  by  laborious  experimenta- 
tion are  so  well  illustrated  by  human  and  animal  experience  in 
general,  that  it  seems  remarkable  that  so  many  physiologists  and 
students  of  nutrition  failed  for  such  a  long  time  to  observe  the 
evidence  and  to  give  it  proper  interpretation.  Experience  at  the 
Wisconsin  Experiment  Station  afforded  the  author  an  oppor- 
tunity to  contrast  the  superior  growth  and  health  of  swine  fed 
on  satisfactory  rations,  with  the  poor  growth  in  the  scrawny, 
stiff-legged  creatures  so  often  seen  on  farms  where  the  owners 
had  not  learned  that  it  is  not  possible  to  keep  a  pig  in  a  dry  lot 
and  feed  it  on  grain,  without  resulting  failure  in  pork  production. 
It  was  at  that  time  known  to  many  shrewd  animal  husbandry- 
men  that  there  are  but  two  methods  for  feeding  swine  for  profit- 
able results.  One  was  to  feed  the  grain  grown  on  the  farm 
while  the  animals  were  running  on  a  good  pasture  such  as  a 
clover  or  alfalfa  field  may  furnish.  The  other  was  to  feed  the 
grain  supplemented  with  liberal  amounts  of  skimmed  milk.  A 
combination  of  these  two  plans  leads  to  still  better  results. 

While  the  investigations  were  in  progress  which  have  led  to 
our  present  understanding  of  the  science  of  nutrition,  observa- 


388     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

tions  such  as  those  emphasizing  the  inadequacy  of  diets  consist- 
ing solely  of  vegetable  products,  the  functions  of  which  are  those 
of  storage  organs,  caused  me  to  inquire  into  the  dietary  habits 
of  man  and  animals  with  a  view  to  finding,  especially  what  rela- 
tively simple  diets,  composed  of  but  one  or  a  few  articles,  were 
at  least  reasonably  successful  in  promoting  well-being.  Such 
an  investigation  into  data  which  Nature  presents  for  contempla- 
tion, revealed  at  once  three  important  facts,  which  serve  as  the 
guiding  principles  upon  which  the  experimental  data  since  ac- 
cumulated have  been  interpreted. 

416.  Many  Instances  of  Successful  Carnivorous  Nutrition. 
— One  of  these  facts,  abundantly  substantiated  by  common  ob- 
servation, is  that  there  are  many  examples  of  animals  subsisting 
entirely  upon  food  derived  from  the  tissues  of  other  animals. 
The  wolf,  lion  and  tiger  are  familiar  examples  among  mammals, 
and  the  eagle,  owl  and  vulture  are  examples  among  birds.  No- 
where do  we  find  more  remarkable  physical  development  than 
among  this  class  of  animals.  It  is  obvious,  therefore,  that  the 
tissues  of  one  animal  contain  everything  which  is  essential  for 
the  nutrition  of  another.  Those  who  accepted  the  old  ideas 
regarding  the  necessary  components  of  an  adequate  diet  saw  no 
reason  for  distinguishing  between  different  types  of  carnivorous 
diets.  Actually  there  are  decided  differences  in  the  dietary 
properties  of  muscle  meats  as  contrasted  with  the  glandular  tis- 
sues. Muscle  meats  are  very  similar  in  their  dietary  properties 
to  the  cereal  grains,  and  in  order  to  make  them  complete  it  is 
necessary  to  supplement  them  with  respect  to  calcium,  sodium 
chlorid  and  all  three  of  the  uncharacterized  "vitamins"  asso- 
ciated with  the  causation  of  the  deficiency  diseases.  The  flesh- 
eating  of  the  carnivorous  animals  is  a  very  different  thing  from 
that  of  civilized  people  in  the  temperate  zones.  For  some  un- 
known reason  the  latter  have  developed  a  special  liking  for 
muscle  cuts  of  meat,  as  steaks,  chops,  etc.,  whereas  the  carnivor- 
ous among  men  and  animals  eat  blood,  glandular  structures  and 
bone  marrow,  fat  and  an  appreciable  amount  of  bone  substance 
in  preference  to  muscle  tissue.  Miss  Simmonds  and  the  author 
have  found  that  suitable  proportions  of  these  tissues  form  very 
satisfactory  diets  for  the  rat,  just  as  they  do  for  the  wild  car- 
nivorae.  Most  people  in  the  past  have  been  satisfied  with  in- 
accurate and  incomplete  descriptions  of  food  habits.  With  the 
greater  knowledge  we  now  possess,  it  is  necessary  to  be  more 
specific  and  accurate  in  all  discussions  of  nutrition  and  diet  (4). 


THE  DIETARY  HABITS  OF  MAN  389 

417.  Other  Tissues  Make  Good  the  Deficiencies  of  Muscle 
Tissue  in   Carnivorous   Feeding. — The   deficiencies   of  muscle 
meats  are  entirely  made  good  by  the  addition  ,._of  blood  which 
furnishes  the_commQn..aalt  which  is  nearly  lacking  in  muscle,  and 
by  such  glandular  organs  as  liver,  kidney,  etc.,  which  furnish  a 
relative  abundance  of  all  three  of  the  uncharacterized  dietary 
factors,    the    anti-ophthalmic,    anti-neuritic    and    anti-scorbutic 
substances.    BgueJ&urnishes  calcium  which  is  not  abundant  in 
any  other  tissues  of  the  body.    All  carnivorous  animals  appear 
to  be  partial  to  fat  rather  than  protein  as  a  source  of  energy  and 
take  large  amounts  of  the  latter  when  it  is  available.    The  most 
satisfactory   carnivorous  diet  would   appear  to  be  such  as  is 
chosen  instinctively  by  the  Eskimos  and  polar  carnivorse.    All  of 
these  as  well  as  those  of  the  cat  and  dog  and  rodent  families 
seem  to  follow  the  practice  of  opening  the  large  veins  of  the  neck, 
when  they  have  killed  an  animal,  and  lap  the  blood  as  long  as  it 
flows.  They  then  open  the  abdominal  cavity  and  eat  of  the  organs 
and  only  after  these  morsels  have  been  disposed  of  do  they  take 
muscle  tissue.    It  is  well  known  that  carnivorous  animals  have 
the  habit  of  finishing  a  repast  by  leisurely  gnawing  a  bone.  Thus 
they  secure  a  properly  balanced  diet  through  selecting  parts  of 
their  victims  which  have  special  dietary  properties. 

418.  Several  Examples  of  Successful  Carnivorous  Nutrition 
in  Man. — There  are  several  examples  of  strictly   carnivorous 
nutrition  in  man  in  which  the   success   attained  is   about  as 
great  as  that  seen  in  animals  on  similar  diets.    Thus  the  Eskimo, 
while  a  small  people,  are  vigorous  and  capable  of  considerable 
exertion.    There  are  climatic  factors  which  may  perhaps  be  re- 
garded as  a  handicap  to  their  well-being,  but  it  is  not  easy  to 
evaluate  these,  for  the  animals  of  the  Arctic  regions  and  the 
Eskimos  as  well  appear  to  be  thoroughly  acclimated  and  to  suffer 
little  from  low  temperatures  or  lack  of  sunlight  over  long  periods. 

The  American  Indians  who  inhabited  the  plains  east  of  the 
Rocky  Mountains  and  subsisted  upon  the  bison,  were  likewise  a 
strictly  carnivorous  people  during  the  greater  part  of  the  year. 
The  cultivated  products  and  wild  fruits  and  berries  formed  at 
best  but  a  slight  variation  from  the  monotonous  flesh  food  sup- 
ply. Lewis  and  Clark,  Parkman  and  other  reliable  observers, 
testify  to  their  being,  in  many  instances,  fine  examples  of  physi- 
cal development.  Like  the  Eskimos  they  ate  the  entire  edible 
part  of  the  animals  which  served  them  as  food.  They  did  not 
even  discard  blood  or  the  alimentary  tract. 


390     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

419.  Lesson  from  the  Health  Experience  of  the  Non-Citizen 
Indians. — There  is  no  better  illustration  of  the  soundness  of  the 
views  regarding  the  types  of  diets  which  succeed  in  inducing 
good  nutrition,  and  the  importance  of  selecting  foods  so  as  to 
produce  combinations  which  are  satisfactory  for  the  maintenance 
of  well-being,  than  the  experience  of  the  non-citizen  Indian  of  the 
United  States.    All  who  observed  the  Indians  in  their  primitive 
state,  agree  that  most  of  them  were  exceptional  specimens  of 
physical  development.    During  two  generations  they  have  dete- 
riorated, physically,  with  few  exceptions,  in  a  manner  more 
marked  than  has  the  last  generation  of  Americans  of  European 
stock.    The  reason  for  this  is  brought  to  light  through  a  con- 
sideration of  the  kind  of  food  to  which  they  have  restricted 
themselves  for  years  past. 

There  is  no  group  of  people  anywhere  having  a  higher  in- 
cidence of  tuberculosis  than  the  non-citizen  Indians.  Wards  of 
the  Government,  they  have  been  provided  with  money  and  land, 
but  have  in  general  shown  no  interest  in  agriculture.  Under 
such  conditions  most  of  them  have  lived  in  idleness  and  have 
derived  their  food  supplies  from  the  agency  stores.  In  addition 
to  meats,  they  have,  therefore,  for  two  decades  or  more,  taken 
large  amounts  of  milled  cereal  products,  syrup  and  molasses, 
and  canned  foods,  such  as  beans,  peas,  corn,  etc.  In  other  words, 
they  have  come  to  subsist  essentially  upon  a  milled  cereal,  tuber 
and  meat  diet.  On  such  a  regimen  their  teeth  have  rapidly  be- 
come inferior,  and  badly  decayed,  and  they  suffer  much  from 
rheumatism  and  other  troubles  which  result  from  invasion  of 
the  blood  stream  through  infected  teeth.  Faulty^dietary.  habits 
are  in  great  measure  to  be  incriminated  for  their  susceptibility 
to  tuberculosis. 

Other  classes  of  Indians  who  have  become  successful  farmers, 
have  not  deteriorated  as  a  result  of  contact  with  civilization, 
except  in  so  far  as  they  have  suffered  from  alcohol  and  venereal 
infections.  The  non-citizen  Indian  has  suffered  most,  not  be- 
cause of  contact  with  civilization,  but  because  of  a  detail  in  con- 
nection with  that  event,  which  can  easily  be  remedied.  He  has 
suffered  little  if  any  more  than  white  people  living  under  similar 
conditions  would  have  done,  and  indeed  are  actually  doing  to- 
day in  many  places. 

420.  Has  Natural  Vigor  Anything  to  Do  with  Susceptibility 
to  Tuberculosis? — There  are  many  who  doubt  whether  faulty 
diet  has  anything  to  do  with  susceptibility  to  tuberculosis,  but 


THE  DIETARY  HABITS  OF  MAN  391 

there  is  little  doubt  that  it  may  be  so.  Experience  has  shown 
that  there  is  no  more  effective  therapeutic  measure  than  proper 
feeding  to  raise  the  recuperative  power  of  the  patient.  If  such 
treatment  affords  greater  prospect  for  throwing  off  the  disease 
once  it  is  established,  it  would  be  decidedly  paradoxical  to  main- 
tain that  highly  satisfactory  nutrition  could  play  no  important 
role  in  protecting  the  individual  against  the  establishment  of  the 
infection.  Appleton  has  pointed  out  that  the  men  of  Labrador 
and  Newfoundland  suffer  greatly  from  tuberculosis,  although 
they  spend  at  least  half  of  the  year  out  of  doors  in  an  invigorat- 
ing climate.  She  states  that  owing  to  the  strong  winds  which 
blow  almost  constantly  during  the  winter,  the  houses  are  ven- 
tilated so  thoroughly  as  to  make  garments  wave  which  are  hang- 
ing in  the  rooms  for  drying.  She  suggests  that  the  faulty  diet 
is  the  predisposing  cause  rather  than  unhygienic  housing. 

421.  The  Food  of  the  Lapps. — An  excellent  example  of  the 
success  of  a  strictly  carnivorous  diet  in  man,  are  the  Lapps. 
These  people  are  scattered  throughout  northern  Scandinavia  and 
the  Murman  coast  and  live  almost  entirely  upon  their  reindeer 
herds  and  on  fish.    They  eat  not  only  meat,  fish  and  fowl,  and 
eggs  of  wild  birds  in  summer,  but  secure  a  fairly  large  amount 
of  milk  from  their 'reindeer.    They  are  a  short  and  heavily  made 
people,  with  good  physical  development  and  great  physical  en- 
durance.   Like  the  Eskimo,  they  must  exert  themselves  greatly 
at  times  in  order  to  maintain  themselves  in  their  inhospitable 
land. 

422.  Attitude  of  the  Carnivora  Toward  Physical  Activity. — \S 
It  appears  that  the  carnivorous  peoples  have  much  the  same  atti- 
tude toward  physical   exertion   as   have   carnivorous   animals. 
When  well  fed  they  are  lethargic  and  remain  idle,  or  do  work 
that  requires  little  exertion.    They  bestir  themselves  only  when 
pressed  by  hunger  to  do  so.     Dr.  Grenfel  states  that  the  Eskimo 
is  an  inferior  fisherman  and  will  catch  one  fish  to  a  white  man's 
ten.    This,  we  may  safely  attribute,  in  part  at  least,  to  intoxi- 
cation from  poisons  of  bacterial  origin,  due  to  putrefaction  of 
protein  in  the  intestine. 

423.  Metchnikoff's    Views    Regarding   the    Generation   of 
Toxic  Products  in  the  Intestine  from  the  Putrefaction  of  Pro- 
tein Food. — The  idea  made  popular  by  Metchnikoff,  that  the 
body  is  injured  by  absorption  of  toxic  substances  formed  in  the 
intestine  through  the  agency  of  putrefactive  bacteria,  rests  upon 
evidence  which  can  hardly  be  doubted.    The  beneficial  effects 


392      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

resulting  from  taking  a  liberal  milk  diet,  especially  milk  which 
has  been  soured  by  the  bacillus  acidophilus,  are  attested  by  a 
great  many  people.  A  very  striking  illustration  of  the  manner 
in  which  a  diet  consisting  largely  of  animal  tissues  modifies  the 
bacterial  flora  of  the  intestine,  and  influences  the  physical  and 
psychical  condition  of  animals,  is  given  by  Herter  and  Kendall 
(5)..  These  investigators  restricted  monkeys  to  a  diet  of  eggs, 
and  cats  to  a  diet  of  meat  for  one  or  two  weeks.  They  then 
shifted  suddenly  to  a  diet  of  milk  and  glucose.  Previous  studies 
had  shown  that  eggs  or  meat  encourage  the  growth  of  putrefac- 
tive organisms  in  the  alimentary  tract,  whereas  milk  and  glu- 
cose stimulates  the  growth  of  fermentative  and  lactic  acid-form- 
ing organisms,  just  as  does  a  diet  consisting  solely  of  carbo- 
hydrates. After  one  or  two  weeks  on  the  milk  and  glucose  diet, 
the  animals  were  returned  to  the  eggs  or  meat,  respectively. 
These  intervals  were  found  sufficiently  long  to  change  entirely 
the  character  of  the  bacterial  flora  of  the  intestine. 

As  the  proteolytic  or  putrefying  type  of  bacteria  began  to  pre- 
dominate, which  occurred  promptly  after  restricting  the  mon- 
keys to  eggs,  the  animals  became  sleepy  and  rested  their  heads 
upon  their  hands  in  a  bowed  position.  They  were  stupid  and 
responded  slowly  to  external  stimuli,  took  their  food  very  de- 
liberately and  manifested  little  interest  in  their  surroundings. 
Not  infrequently  after  a  hearty  meal  the  animals  would  spend 
much  time  trying  to  bite  the  woodwork  of  the  cage.  The  urine 
voided  was  of  small  volume  and  highly  colored,  and  amounted 
to  approximately  half  that  produced  from  the  milk-carbohydrate 
diet.  As  the  protein-digesting  bacteria  became  established,  in 
the  intestine  the  amount  of  products  of  putrefaction  which  ap- 
peared in  the  urine  increased  markedly. 

When  the  animals  were  changed  to  the  milk-glucose  diet,  both 
the  psychical  and  physical  attitude  underwent  a  great  change. 
They  no  longer  held  their  heads  in  their  hands,  but  assumed  an 
erect  posture  and  were  alert  and  bright,  and  showed  a  keen  inter- 
est in  their  surroundings.  Their  appetites  became  sharp  and  the 
food  was  consumed  with  more  avidity.  The  eyes,  which  were 
dull  and  lusterless  while  on  the  egg  diet,  became  bright.  They 
no  longer  attempted  to  chew  the  woodwork  of  the  cage.  The 
products  of  putrefaction  of  protein  almost  disappeared  from 
the  urine.  The  evidence  from  human  experience  seems  suffi- 
cient to  warrant  the  conclusion  that  similar  changes  in  the  diet 
of  man  induce  similar  modification  in  the  bacterial  flora  of  the 


THE  DIETARY  HABITS  OF  MAN  393 

intestinal  tract.  One  may  safely  conclude  that  excessive  con- 
sumption of  meat,  with  but  small  and  insignificant  amounts  of 
carbohydrates,  tends  to  promote  the  generation  of  toxic  sub- 
stances which  induce  lethargy  in  both  man  and  animals. 

424.  Meat-Eating  in  America  Is  Very  Different  from  Prac- 
tices of  the  Carnivora. — There  is  considerable  misunderstanding 
as  to  the  effects  of  taking  liberal  amounts  of  meat.    The  meat 
eating  of  the  people  of  America  and  parts  of  Europe  is  largely 
confined  to  muscle  cuts.     It  is  to  be  regretted  that  excessive 
meat  eaters  very  frequently  derive  the  greater  part  of  the  re- 
mainder of  their  food  supply  from  degerminated  cereal  products 
and  tubers.    Such  diets  are  faulty  in  several  respects.    They  tend 
to  contribute  to  the  early  deterioration  of  the  tissues,  and  for 
reasons  quite  apart  from  the  amount  of  meat  consumed.    Re- 
sults due  to  faulty  diet  are  not  infrequently  attributed  to  the 
meat  fraction,  when  in  reality  other  components  of  the  food 
supply  may  be  said  to  contribute  in  an  important  degree  to  the 
bad  effects  observed.     It  frequently  happens  that  the  other  food 
components  fail  to  supplement  the  meat,  and  correct  its  defi- 
ciencies.   Success  has  been  attained  with  laboratory  animals  re- 
stricted to  a  diet  of  muscle  meat  supplemented  with  such  sub- 
stances as  are  necessary  to  make  it  a  complete  food.    The  good 
development  and  vigor  of  carQiy.Qj^ua_^nimals  lies  in  the  choice 
of  parts  of  their  victims  so  as  to  make  a  satisfactory  adjustment 
of  the  necessary  food  essentials.     This  success  serves  to  illus- 
trate a  principle  which  must  not  be  lost  sight  of  in  interpretation 
of  the  cause  of  nutritive  disturbances.    The  diet  must  be  con- 
sidered as  a  whole,  and  an  accurate  estimate  made  as  to  the 
degree  of  completeness  of  every  essential  factor.    Since,  in  this 
country  the  term  "high  protein  diet"  is  generally  synonymous 
with  "high  meat  diet,"  it  will  be  seen  that  disturbances  of  nutri- 
tion believed  to  be  referable  to  excessive  protein  ingestion,  may 
well  be  due,  not  so  much  to  the  amount  of  protein  eaten,  but  to 
failure  to  take  a  complete  diet.    Such  a  diet  is  only  to  be  secured 
through  the  proper  selection  of  foods  which  make  good  each 
other's  deficiencies.    It  is  the  completeness  of  the  diet  rather 
than  an  unusual  amount  of  some  one  factor  which  is  the  most 
important  consideration. 

425.  The  Teeth  of  the  Carnivora  Were  Excellent. — The 
teeth  of  the  carnivorous  animals  and  of  carnivorous  man  were 
of  excellent  quality  so  long  as  they  adhered  to  their  primitive 
dietary  habits.    With  the  change  to  a  new  type  of  diet,  such*  as 


394     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

is  now  common  in  Europe  and  America,  savage  peoples  and 
others  who  have  modified  their  diet  in  a  similar  manner,  there 
has  resulted  rapid  deterioration  of  the  teeth  and  caries  have 
become  common.  The  teeth  of  the  primitive  Eskimo  were  ex- 
cellent. According  to  Stefansson,  there  was  no  word  for  tooth- 
ache in  their  language.  To-day  the  younger  generation  of  the 
Eskimo  dwelling  along  the  Arctic  coast  of  Alaska  have  teeth 
as  defective  as  those  of  children  in  the  States.  They  have  been 
brought  up  in  great  measure  on  foods  such  as  are  available  in 
the  grocery  stores  in  the  United  States,  viz.:  on  flour,  sugar, 
molasses,  muscle  meats  and  fish.  It  is  a  far  cry  from  such  a 
diet  to  that  of  their  forefathers,  although  this  could  be  discov- 
ered only  as  the  result  of  the  accumulated  data  secured  through 
animal  experimentation. 

426.  The  Nutrition  of  the  People  of  Iceland. — A  most  in- 
teresting experience  is  that  of  the  people  of  Iceland.  The  island 
was  settled  in  the  ninth  century  by  colonists  from  Scandinavia 
and  Ireland.  The  colonists  took  with  them  cattle  and  sheep, 
but  no  poultry.  The  latter  were  not  introduced  until  about  a 
century  ago.  Their  diet  was  practically  carnivorous  in  charac- 
ter for  several  hundred  years.  Since  agriculture  did  not  prove 
profitable,  they  subsisted  on  milk,  mutton,  fish,  and  in  some 
parts  of  the  island  during  the  summer,  eggs  were  added  to  the 
fare.  Very  little  vegetable  food  was  eaten.  The  health  condi- 
tions on  this  regimen  were  good  and  dental  caries  were  unknown 
until  after  about  1850.  Stefansson  exhumed  96  skulls  from  a 
cemetery  dating  from  the  ninth  to  the  thirteenth  centuries  and 
presented  them  to  the  Peabody  Museum  of  Harvard  University. 
These  have  been  described  by  Hooton  (6) ,  who  found  that  there 
were  no  evidences  of  caries  in  any  of  them.  There  were  but 
three  or  four  defective  teeth  in  the  entire  series,  and  these  had 
suffered  mechanical  injury.  During  the  last  half  century  the 
incidence  of  caries  has  steadily  increased  in  Iceland,  and  ap- 
parently because  of  changes  in  the  character  of  the  diet.  Every- 
where in  Europe  and  America  during  the  last  century  the  use 
of  degerminated  cereal  products  such  as  bolted  wheat  flour, 
degerminated  corn-meal  and  polished  rice  has  steadily  increased, 
owing  to  the  extension  of  commerce  and  the  changed  conditions 
with  respect  to  the  relative  numbers  of  urban  and  rural  popu- 
lation. Not  only  has  the  amount  of  cereal  products  consumed 
greatly  increased,  but  the  modern  milling  methods  have  greatly 
reduced  their  quality  by  removing  the  germ  and  the  bran  layer. 


THE  DIETARY  HABITS  OF  MAN  395 

It  is  very  suggestive  that  such  diets  as  we  are  discussing  as  in 
use  in  recent  years  are  so  poor  as  to  produce  faulty  teeth  in 
experimental  animals,  and  that  the  teeth  of  mankind  have 
deteriorated  so  rapidly  within  the  last  century. 

427.  The  Diet  of  the  Inhabitants  of  the  Hebrides. — A  diet 
very  similar  to  that  used  in  Iceland  has  also  long  been  customary 
in  certain  islands  in  the  Hebrides.    The  only  agricultural  crops 
which  are  very  successful  are  turnips  and  potatoes.    Cattle  are 
kept  in  sufficient  numbers  to  give  one  or  two  cows  to  each  fam- 
ily.   Some  oatmeal  is  available  and  forms  a  constant,  though 
not  an  abundant  constituent  of  the  diet.     Many  of  the  men  are 
engaged  in  fishing  and  the  unsalable  parts  of  the  cod  form  a 
regular  and  prominent  part  of  the  food  supply.    Milk,  cod  heads 
stuffed  with   livers,   turnips,   potatoes   and   oatmeal   constitute 
almost  the  sole  food  supply  of  the  poor  crofters.    The  health  of 
the  people  is  excellent  except  that  the  incidence  of  tuberculosis 
among  the  natives  is  high. 

The  susceptibility  of  these  people  to  tuberculosis  is  due  in 
great  measure  to  the  irritation  of  the  l 
breathing  of  the  smoke  of_  peat  fires.  Most  of  the  houses  are 
very  primitive  turf  structures  without  windows,  or  with  windows 
which  are  fixed.  The  roofs  are  thatched  and  are  without  chim- 
neys. Peat  fires  are  kept  burning  all  day  and  most  of  the 
night,  and  the  only  means  of  exit  for  the  smoke  is  through 
the  thatch  or  through  the  doorway.  This  annoyance  is 
tolerated  because  of  the  belief  that  the  thatch,  which  is 
renewed  annually  and  is  applied  to  the  land  for  fertilizer, 
is  made  more  valuable  by  being  saturated  with  the  products 
of  incomplete  combustion  of  the  peat.  The  cows  are  actually 
housed  in  one  end  of  the  house  serving  as  the  human  habitation, 
and  the  manure  is  removed  but  once  a  year  and  placed  directly 
on  the  land.  The  lungs  are  injured  by  the  irritating  smoke 
and  this  is  believed  to  predispose  them  to  tuberculosis. 

428.  No   Rickets   Among   the    Children   of  the  Island   of 
Lewis  in  the  Hebrides. — Perhaps  the  most  spectacular  thing 
about  the  relation  of  the  diet  to  health  in  the  Island  of  Lewis  in 
the  Hebrides,  is  the  condition  of  the  infant  population.    The 
babies  are  rarely  taken  out  of  the  dark  and  smoky  houses,  ex- 
cept for  a  few  minutes  at  a  time  in  bright  weather,  because  of 
the  numerous  duties  of  the  mothers.    They  are,  however,  uni- 
versally nursed  and  by  mothers  who  are  taking  a  diet,  which  al- 
though unattractive  to  the  American  palate  is  quite  satisfactory 


396     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

for  the  maintenance  of  growth  and  of  vigor  in  the  child  and  adult, 
and  for  the  secretion  of  milk  by  the  lactating  mother.  The  greater 
part  of  their  diet  is  cod  heads  stuffed  with  a  mixture  of  chopped 
livers  and  oatmeal,  milk,  eggs  and  tea,  with  rather  limited 
amounts  of  oatmeal,  bread,  butter  and  potatoes.  It  is  prin- 
cipally a  carnivorous  diet,  and  contains  only  adjuvants  of  veg- 
etable origin.  The  infants  are  all  free  from  rickets,  which  is  so 
prevalent  in  England  and  Scotland  as  to  constitute  a  national 
health  problem.  In  fact,  the  infant  mortality  in  this  island  is 
as  low  as  anywhere  in  the  British  Isles.  Although  the  mothers 
suffer  from  over  exertion  in  agricultural  labor  and  otherwise, 
their  infants  are  far  better  nourished  than  are  tens  of  thousands 
in  America  at  the  present  time,  whose  mothers  are  living  on 
diets  rich  in  cereals,  potatoes  and  muscle  meats. 

429.  Good  Nutrition  Goes  Far  Toward  Offsetting  the  Ef- 
fects of  Bad  Hygienic   Surroundings". — This   illustrates  in  a 
very  satisfactory  manner  a  fact  which  has  been  many  times 
demonstrated  in  animal  husbandry  experience,  viz.:   that  very 
good  results  can  be  secured  in  physical  development  in  young 
animals  which  are  abundantly  supplied  with  a  satisfactory  diet, 
even  when  the  hygienic  surroundings  are  bad.    This  is  not  a 
defence  of  poor  sanitation,  but  affords  a  basis  for  comparison 
of  the  relative  importance  of  diet  and  other  factors  which  in- 
fluence development  and  vitality.    The  same  may  be  said  of 
exercise  as  contrasted  with  diet.    Young  bulls  are  often  given 
wholly  inadequate  opportunity  for  activity,  yet  on  a  highly  satis- 
factory diet  they  develop  into  remarkably  fine  animals.    Exer- 
cise is  of  course  a  very  essential  thing  to  perfect  health  and  the 
long  maintenance  of  vitality,  but  Highly  satisfactory  nutritive 
conditions  are  capable  of  protecting  young  animals  to  a  surpris- 
ing degree  against  physical  and  hygienic  handicaps. 

430.  The  Rearing  of  Young  Lions  in  Captivity. — Another 
illustration  of  how  modifications  of  the  diet'  which   formerly 
would  have  seemed  unimportant,  may  make  a  difference  be- 
tween failure  and  success  in  growth  and  development  is  afforded 
in  the  experience  of  those  who  have  attempted  to  rear  young 
carnivora  in  captivity.    It  was  not  possible  until  within  recent 
years  to  rear  young  lions  in  zoos  or  circuses,  but  to-day  this  is 
being  done  successfully  in  several  places.    Formerly  it  was  the 
custom  to  give  lions  a  large  bone  with  a  quantity  of  muscle 
attached.    The  animals  ate  the  muscle  tissue  and  attempted  to 
gnaw  the  bone,  but  this  was  too  large  and  hard  to  permit  them 


THE  DIETARY  HABITS  OF  MAN  397 

to  secure  much  of  its  substance.  There  was  danger  of  choking 
on  bones  which  might  be  splintered,  or  which  could  not  be 
cracked,  yet  which  were  so  large  as  to  be  swallowed  with  diffi- 
culty. They  were,  in  other  words,  restricted  too  largely  to 
muscle  meat  and  to  an  inadequate  amount  of  bone  substance. 
Under  these  conditions  young  lions  invariably  developed  rickets 
and  had  to  be  killed  because  they  were  so  deformed  as  to  be 
unfit  for  exhibition.  Now  it  has  been  learned  that  the  diet 
should  consist  of  liver  and  other  glandular  organs,  such  bones  as 
shoulder  blades  which  are  easily  consumed,  fat,  and  at  intervals 
of  a  few  days  pigeons  or  rabbits,  the  entire  carcasses  of  which 
can  be  eaten.  Muscle  tissue  is  fed  rather  sparingly.  Under  such 
management,  it  is  easily  possible  to  secure  satisfactory  nutrition 
in  these  animals.  The  reason  why  such  a  practice  succeeds 
where  the  older  one  failed,  is  now  understood  in  the  light  of  our 
knowledge  of  the  special  dietary  properties  of  each  of  the  tissues 
of  the  animal  body. 

431.  The  Carnivorous  Diet  May  Be  Highly  Satisfactory. — 
It  will  be  readily  appreciated  from  what  has  been  said,  that 
both  in  human  and  animal  experience,  the  carnivorous  diet,  when 
properly  selected,  of  the  diet  which  is  largely  carnivorous  but 
supplemented  with  moderate  amounts  of  vegetable  foods,  may 
prove  highly  satisfactory  for  the  promotion  of  growth  and  the 
maintenance  of  vigor  and  longevity. 

432.  The  Oriental  Diet. — We  may  next  consider  a  type  of 
diet  which  has  served  to  nourish  more  than  half  of  the  human 
race  from  time  immemorial,  and  is  still  depended  upon  by  more 
than  half  of  mankind.    This  type  is  that  used  so  extensively  in 
China,  Japan,  the  Philippines  and  elsewhere  in  the  Orient.    In 
it  the  vegetative  parts  of  plants,  the  leaves,  form  a  very  promi- 
nent part  of  the  food  supply. 

433.  Many  Examples  of  Successful  Nutrition  Among  Leaf 
Eating  Animals. — One  of  the  three  facts  which  stood  out  promi- 
nently in  my  consideration  of  the  types  of  diets  which  had  suc- 
ceeded in  human  experience  and  with  animals,  was  that  certain 
peoples  and  many  animals  were  thriving  on  diets  in  which  the 
leaves  of  plants  were  important  articles   of  food.    Thus  the 
grazing  animals  may  live  throughout  their  lives  on  grass  or 
other  palatable  forage  plants.    All  the  animals  of  the  cattle, 
horse,  sheep,  goat,  deer  and  other  types,  in  their  early  history 
had  no  grain,  and  subsisted  entirely  upon  grass.    The   bison 
never  had  anything  else  throughout  life.    The  giraffe  feeds  upon 


398      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

the  leaves  of  trees  and  shrubs.  This  idea  seemed  very  fertile, 
when  one  considered  that  swine  had,  in  our  experimental  trials, 
failed  so  signally  in  their  nutrition  when  confined  to  a  diet  of  a 
cereal  grain  or  mixture  of  several  cereals  such  as  wheat,  maize  or 
oats.  On  reflection,  it  naturally  occurred  to  me  to  consider  the 
function  of  the  seed  as  contrasted  with  the  leaf.  The  former  is 
a  storage, tissue,  formed  to  supply  the  plantlet  which  develops 
during  germination,  with  sufficient  nutriment  to  enable  it  to 
form  a  root  and  leaf  system.  After  this  stage  it  is  independent 
of  further  aid,  and  can  secure  everything  it  needs  from  the  soil 
and  air.  The  nutritive  needs  of  a  plant  are  very  different  from 
those  of  an  animal.  The  plantjcan  synthesize  its  proteins  and 
carbohydrates  as  well  as  all  the  other  components  of  its  complex 
structure.  The  animaLjnust  secure  these  ready  formed  or  it 
will  perish.  The  leaf,  on  the  other  hand,  is  the  laboratory  of 
the  plant.  It  is  here  that  the  numerous  complex  organic  syn- 
theses take  place.*  We  may  reasonably  assume  that  there  are 
structures  and  chemical  substances  here  which  would  not  be 
found,  at  least  in  abundance  in  a  seed.  Were  not  the  dietary 
properties  of  the  leaf  superior  to  those  of  the  seed?  Experi- 
mental trials  showed  clearly  that  this  surmise  was  correct. 

434.  There  Are  No  Strictly  Vegetarian  Peoples  in  the 
Sense  That  Animals  Are. — There  are  no  strictly  vegetarian 
peoples  in  the  sense  that  certain  animals  are.  The  human  ali- 
mentary tract  is  not  sufficiently  capacious  to  admit  of  eating 
liberally  of  coarse  herbage.  There  are  a  considerable  number 
of  people  in  the  Orient  who  take  very  liberal  amounts  of  green 
leafy  vegetables  as  a  supplement  to  a  diet  which  is  otherwise 
unsatisfactory  and  is  much  like  that  in  use  by  many  people  in 
the  United  States.  The  diet  referred  to  is  one  consisting  prin- 
cipally of  cereal  grains,  legume  seeds,  tubers  and  fleshy  roots, 
and  meats.  Fish,  eggs  and  poultry  are  eaten  in  varying  amounts, 
but  the  outstanding  feature  of  their  diet  is  the  large  amount 
of  green  leafy  vegetables  which  enter  into  it.  This  type  of  diet 
may  be  an  excellent  one,  but  it  is  probable  that  in  human  ex- 
perience this  is  rarely  realized.  The  people  of  the  north  of 
China,  especially  in  the  Shantung  peninsula,  are  frequently  fine 
specimens  of  physical  development.  Thousands  of  these  were 
brought  to  France  as  laborers  during  the  war.  In  this  part  of 
the  country  wheat  is  eaten  largely  instead  of  rice,  and  the  entire 
grain  is  eaten.  Further  south  more  rice  enters  into  the  diet,  and 
owing  to  a  peculiar  and  baseless  notion  of  its  superior  attractive- 


THE  DIETARY  HABITS  OF  MAN  399 

ness,  polished  rice  is  preferred.  This,  it  has  already  been  pointed 
out,  is  very  inferior  in  its  dietary  properties  to  unpolished  rice. 
These  and  other  factors  which  may  vary  from  time  to  time,  and 
which,  a  few  years  ago  would  have  been  regarded  as  of  no  signifi- 
cance, actually  may  be  very  important  in  determining  the  quality 
of  the  diet.  At  best,  it  is  a  diet  which  is  sufficient,  but  in  which 
there  is  little  margin  of  safety.  The  special  role  of  the  leafy 
vegetables  which  it  contains  is  to  increase  the  calcium  content 
and  the  fat-soluble  A  content  of  the  food  supply.  Where  eggs 
are  eaten  freely  these  supplement  the  food  well  with  respect  to 
the  latter  substance. 

435.  The  Importance  of  Certain  Articles  in  the  Oriental 
Diet. — It  can  be  readily  appreciated  that  moderate  variations 
in  the  amounts  of  leafy  structures  eaten,  the  amounts  of  eggs, 
and  the  extent  to  which  polished  rice  enters  into  the  diet  in  place 
of  whole  rice  or  other  cereal  grain,  will  have  a  most  important 
bearing  upon  whether  the  diets  of  this  type  suffice  for  the  main- 
tenance of  well-being.    These  variable  factors  will  also  deter- 
mine whether  there  is  an  excess  of  any  of  the  several  factors 
in  the  diet,  over  the  minimum  on  which  a  child  can  grow  up 
and  live  what  is  ordinarily  regarded  as  an  average  span  of  life. 
When  a  diet  fulfils  these  conditions  it  passes  as  satisfactory,  but 
there  is  good  reason  now,  because  of  the  results  of  the  experi- 
mental studies  of  the  last  few  years,  to  question  whether  any 
diet  is  as  satisfactory  as  it  is  possible  to  make  it.    The  final 
goal  is  to  strive  to  discover  whether  any  dietary  regimen  in  use 
by  man  best  promotes  his  vitality  to  the  maximum.    There  is 
good  reason  to  believe  that  the  Oriental  diet  of  the  type  under 
discussion,  is  at  best,  but  a  second  rate  one,  and  that  it  is  not 
capable  of  meeting  the  needs  of  the  growing  child  except  in 
special  cases  where  the  most  fortunate  selection  of  articles  is 
made.    It  does  not,  in  general,  support  vigorous  health  and 
stimulate  effort  to  an  advanced  age. 

436.  No  Foods  in  China  and  Other  Oriental  Countries  Suit- 
able for  Feeding  Young  Children. — It  is  certainly  true  that  the 
diet  of  China,  Japan  and  other  countries  in  which  the  same 
general  habits  prevail,  is  not  suited  for  the  proper  nutrition  of 
young  children.    It  has  always  been  the  practice  of  mothers 
there  to  nurse  their  infants  for  very  long  periods,  even  four  or 
five  years  being  not  unusual.    The  early  weaning  of  infants 
which  is  so  widely  practised  in  Europe  and  America,  is  made 
possible  because  of  the  availability  of  an  abundance  of  milk  of 


400     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

the  cow  and  goat.  If  the  Orientals  weaned  their  children  at 
nine  to  twelve  months  of  age  as  is  the  custom  in  this  country, 
their  infant  mortality  would  be  very  great,  for  their  foods  are 
not  suitable  for  feeding  to  young  children  and  older  infants. 

In  certain  respects  this  is  to  the  advantage  of  the  Oriental 
infants  but  in  others  it  is  a  disadvantage.  Thus,  since  the 
mothers  are,  in  general  taking  diets  which  are  sufficient  to  meet 
their  bodily  needs  in  a  fairly  satisfactory  manner  over  a  con- 
siderable number  of  years,  they  are  able  to  secrete  milk  of  mod- 
erately good  quality  and  for  many  months  or  even  for  several 
years.  Their  infants  are,  therefore,  protected  against  the  intes- 
tinal disturbances  which  are  so  frequently  the  result  of  feeding 
milk  which  is  in  bad  bacteriological  condition  in  this  country. 
They  likewise  fail  to  suffer  from  rickets  as  do  a  large  number 
of  children  in  Europe  and  America.  Their  mother's  milk  or 
that  of  a  wet  nurse  is  the  most  appropriate  food  for  them,  and 
they  in  general  during  the  nursing  period,  but  no  longer,  fare 
better  than  do  those  children  in  our  country  whose  mothers  are 
limiting  their  diets  largely  to  bolted  wheat  flour  and  other  de- 
germinated  cereal  products,  potatoes  and  muscle  meats,  the  meat, 
bread  and  potato  type  of  diet.  On  this  they  are  unable  to 
secrete  milk  of  good  quality  and  after  a  few  weeks  or  months 
their  milk  supply  falls  off  or  becomes  of  poor  quality  and 
weaning  becomes  imperative. 

437.  Difficult  to  Maintain  Normal  Nutrition  in  the  Child 
After  Weaning. — After  weaning,  however,  it  appears  that  the 
diet  of  the  Oriental  child  is  ordinarily  less  satisfactory  than  that 
of  the  American  or  European  child.  This  is  due  in  great  meas- 
ure to  the  lack  of  milk,  of  which  the  Chinese,  Japanese  and 
Filipinos  have  never  had  a  supply  until  within  recent  years 
when  canned  milks  have  been  introduced.  There  is  some  defi- 
nite evidence  to  which  one  can  point  in  support  of  this  view. 
Fifteen  years  ago  there  was  a  great  influx  of  "picture  brides" 
from  Japan  into  California  and  other  Pacific  coast  cities.  We 
have,  therefore,  a  large  number  of  children  in  this  country  of 
Japanese  parentage.  Both  boys  and  girls  are  larger  at  all  ages 
than  are  Japanese  children  born  and  reared  in  Japan  (7).  Who 
would  doubt  that  it  is  the  superior  food  which  they  receive 
which  makes  them  outgrow  their  relatives  across  the  ocean? 
The  Chinese  are  smaller  in  the  south  than  they  are  in  the  north, 
where  wheat  and  millet  replace  rice  in  the  diet.  In  southern 
China  polished  rice  is  the  most  desired  cereal.  This  use  of  a 


THE  DIETARY  HABITS  OF  MAN  401 

degerminated  and  decorticated  cereal  makes  a  very  important 
difference  in  the  satisfactoriness  of  the  mineral  content  of  their 
diet,  and  is  probably  sufficient  to  account  for  their  relative  physi- 
cal inferiority  as  compared  with  their  northern  neighbors.  There 
is  but  one  explanation  for  their  liking  for  polished  rice,  and  that 
is  custom.  Polished  rice  is  inferior  in  every  respect  to  the  un- 
polished grain,  but  since  it  is  fashionable  to  eat  the  former  kind, 
those  whose  diet  is  much  simpler,  as  is  for  example  the  poor 
laborers,  who  derive  their  sustenance  largely  from  rice  and  fish 
and  a  few  vegetables,  take  pride  in  feeling  that,  however  hard 
their  lot  may  be  in  other  respects,  their  rice  is  as  white  as  their 
more  fortunate  neighbors'.  The  ease  with  which  a  firm  and 
established  demand  for  bolted  flour,  polished  rice  and  other 
degerminated  cereal  products  has  been  created  through  adver- 
tising, shows  how  unsafe  is  appetite  as  a  guide  to  the  selection 
of  food. 

438.  Heredity  Versus  Nutrition  as  a  Factor  Determining 
the  Size  of  a  People. — The  question  has  been  raised  on  several 
occasions  when  the  size  of  a  people  has  been  mentioned  in  con- 
nection with  the  nature  of  their  food,  whether  size  is  not  entirely 
a  racial  characteristic,  and  is  inherited,  rather  than  being  deter- 
mined by  such  agencies  as  nutrition.  It  seems  to  me  that  we 
have  some  very  good  evidence  on  this  point  in  the  histories  of 
our  rat  families  described  in  the  preceding  chapter.  When  the 
nutrition  of  these  animals  fell  just  under  a  certain  standard, 
there  was  no  easily  observable  sign  of  malnutrition,  their  ap- 
pearance and  fertility  remaining  such  that  they  would  be  judged 
by  anyone  to  be  "normal,"  yet  the  size  diminished  from  genera- 
tion to  generation.  This  is  not,  of  course,  set  forth  as  an  in- 
heritance of  an  acquired  character,  but  only  as  evidence  that 
physically  inferior  parents  tend  to  pass  on  their  defective  con- 
stitution to  their  offspring.  The  prompt  increase  in  size  of 
Japanese  children  born  in  California  and  fed  upon  the  products 
of  its  farms,  over  the  sizes  characteristic  of  children  of  the  same 
ages  in  Japan,  would  seem  to  harmonize  well  with  the  view 
which  we  have  come  to  hold  concerning  the  quality  of  the  Orien- 
tal diet.  Horses  introduced  into  the  Shetland  and  Orkney 
Islands  have  degenerated  in  size  and  that  size  is  inherited  in 
their  offspring.  Here  again  we  see  the  effects  of  such  a  scanty 
and  somewhat  inadequate  food  supply  that  the  animals  are 
stunted  in  their  growth.  Perhaps  it  is  more  accurate  to  say 
that  their  food  supply  is  sufficiently  scant  and  precarious  in  the 


402     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

winter  season  to  interfere  with  their  growth,  and  that  their  small 
size  is  due  to  permanent  stunting  from  periodic  starvation 
through  several  generations.  The  inferior  physical  development 
of  these  horses  to-day  must  be  admitted,  and  is  certainly  not  due 
in  any  great  measure  to  artificial  selection.  In  another  region 
of  the  world  where  pasturage  is  abundant  throughout  the  year, 
there  is  every  probability  that  the  size  of  these  animals  would 
increase. 

439.  The  Climate  of  California  Not  so  Stimulating  as  That 
of  Japan. — According  to  Huntington,  the  climate  of  California 
as  a  whole  is  less  stimulating  than  is  that  of  Japan,  and  is, 
therefore,  less  satisfactory  from  the  physiological  standpoint  (8) . 
He  bases  this  belief  on  the  results  of  his  studies  which  show  that 
wherever  the  climate  has  a   favorable  range  of  temperature 
change  from  day  to  night,  and  is  characterized  by  storminess 
of  the  cyclonic  type,  there  the  people  show  energy  and  aggres- 
siveness.   Japan,  in  respect  to  its  storminess  ranks  as  one  of  the 
most  stimulating  regions  of  the  world.    It  seems  remarkable 
that  a  very  favorable  climate,  which  all  would  doubtless  agree 
Japan  has,  should.be  less  favorable  to  the  growth  of  its  children 
than  a  less  stimulating  climate,  if  there  were  not  another  factor 
at  least  operating  which  is  less  favorable  in  Japan  than  in 
America.    That  this  factor  is  the  diet,  there  can  be  little  room 
for  doubt,  since  in  several  generations  a  diet  of  the  type  there 
in  common  use  would  effect  a  decrease  in  the  size  of  animals 
restricted  to  it. 

440.  Greater  Danger  in  a  Simple  and  Monotonous  Diet 
i      Than  in  a  Varied  One. — It  is  true  of  any  people,  that  those  with 

means  live  in  better  houses  and  have  a  more  varied  and  abun- 
dant food  supply  than  do  the  less  prosperous  part  of  the  popu- 
lation. The  poorer  classes  among  Orientals,  as  in  Western 
nations,  live,  generally  speaking,  on  a  simpler  diet  than  the 
well-to-do.  While  it  is  true  that  simplicity  in  diet  is  perfectly 
safe  and  satisfactory  provided  the  food  is  wisely  chosen,  there 
is  more  danger  that  a  food  supply  which  is  monotonous  and  con- 
tains but  few  articles,  will  be  sufficiently  poor  to  make  its  effects 
clinically  recognizable,  than  would  be  the  case  if  the  food  offered 
greater  variety.  This  might  be  true  even  though  the  faults  in 
the  diet  were  of  the  same  magnitude  as  those  of  the  simpler 
one,  for  in  the  former  case  the  frequent  changes  in  menus  would 
cause  an  alternation  of  the  factors  which  depart  from  the  nor- 
mal, whereas  in  the  latter  case  the  same  factors  would  tend  to 


THE  DIETARY  HABITS  OF  MAN  403 

be  faulty  over  a  long  period  and  their  effects  would  be  cumulative 
and  would  accordingly  do  more  damage. 

It  is  for  the  reason  just  stated  that  the  poorer  classes  in  sev- 
eral parts  of  the  world  suffer  from  beri-beri.  Any  people  hav- 
ing a  relatively  high  incidence  of  any  deficiency  disease,  are  cer- 
tainly to  be  regarded  as  a  group  all  members  of  which,  so  far 
as  they  subsist  upon  a  similar  type  of  diet,  are  borderline  cases 
of  malnutrition  whether  or  not  they  show  any  clinically  recog- 
nizable signs  of  disease.  There  is  good  reason  to  believe  that 
the  Japanese  people  can  become  larger  and  more  powerful  physi- 
cally if  they  can  institute  certain  changes  in  the  character  of 
their  diet. 

441.  Importance  of  Milk  in  the  Diet  of  Western  Nations 
and  of  Pastoral  Peoples. — The  third  fact  which  became  clear 
in  connection  with  the  examination  of  the  dietary  practices  of 
man  and  animals,  was  that  diets  which  were  derived  from  mis- 
cellaneous sources  such  as  cereal  grains,  legume  seeds,  tubers, 
fleshy  roots,  with  or  without  meats,  but  supplemented  with  lib- 
eral amounts  of  milk,  sufficed  to  maintain  satisfactory  growth 
and    marked    vigor.    Animal    husbandry    experience    afforded 
strong  evidence  of  the  excellence  of  milk  as  food  for  growing 
animals,  but  especially  of  its  high  value  for  supplementing  other 
foods  such  as  the  cereals  in  pork  production.    It  was  recognized 
generally,  that  the  two  best  methods  for  promoting  growth  in 
swine  were,  either  to  combine  milk  production  with  a  creamery, 
so  that  the  skim  milk  could  be  returned  to  the  farm  and  fed  to 
hogs  as  a  supplement  to  corn,  or  to  feed  the  grain  raised  on  the 
farm  to  hogs  which  were  supplied  a  good  pasture.    The  explana- 
tion of  the  cause  of  success  of  either  of  these  practices  was  not 
understood,  but  we  now  appreciate  the  unique  significance  of 
the  value  of  the  mineral  content  and  the  fat-soluble  A  content, 
as  well  as  of  the  supplementary  value  of  the  proteins  of  the 
leaves  of  our  best  forage  plants,  and  of  milk,  in  making  good  the 
deficiencies  of  the  grains  in  these  factors.    The  great  value  of 
skim  milk  in  pork  production  made  it  very  desirable  to  find  a 
substitute  for  milk  in  the  rearing  of  calves,  and  much  effort  has 
been  expended  in  several  of  the  Agricultural  Experiment  Sta- 
tions in  America  to  find  a  calf  feed  which  was  derived  from 
foods  other  than  milk  which  would  prove  wholly  satisfactory. 
The  results  of  these  efforts  have  supported  the  view  that  there 
is  no  effective  substitute  for  milk. 

442.  The  Vigor  of  Pastoral  Nomads. — When  we  turn  to 


404      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

human  experience  with  diets  rich  in  milk,  some  most  interesting 
observations  are  met  with.  Certain  regions  have  throughout 
history,  produced  vigorous  and  aggressive  people.  The  Aryans 
and  Mongols  developed  in  the  high  pasture  lands  of  Central  Asia, 
where  agriculture  did  not  yield  a  return  for  labor,  and  where 
the  care  of  flocks  and  herds  formed  the  chief  means  of  sub- 
sistence. Here  in  a  climate  characterized  by  extremes  of  heat 
and  cold  and  of  drought  have  originated  the  virile  peoples  who 
have  become  the  possessors  of  the  lands  in  every  direction  where 
the  climate  and  soil  were  more  favorable  to  an  easy  existence. 
Abstemious  nomads,  who  knew  no  indulgence,  and  were  every 
few  years  brought  to  face  disaster  through  a  scantier  rainfall 
than  usual,  left  their  homes  in  wave  after  wave  and  dispos- 
sessed their  neighbors  in  more  favored  lands.  But  in  those 
more  favorable  circumstances  where  they  came  as  conquerors, 
they  not  infrequently,  in  time  degenerated  into  ease-loving 
agriculturists. 

443.  The  Jews  Were  Originally  Pastoral  Nomads. — The 
migration  of  the  Jews  under  the  leadership  of  Abraham  and 
Lot,  from  the  dry  plains  of  Mesopotamia,  bringing  their  flocks 
and  herds,  and  appropriating  to  their  own  use  the  better  watered 
lands  of  Palestine,  represents  another  example  of  the  vigor  and 
determination  as  well  as  manly  qualities  of  other  sorts,  developed 
by  a  race  of  herdsmen.    The  Bedouins  of  Arabia  and  the  Taureg 
tribes  of  the  Sahara  are  other  examples  of  peoples  of  great  physi- 
cal perfection  and  high  mental  attainments,  subsisting  under  the 
most  adverse  conditions  of  climate  and  aridity,  by  converting  a 
scanty  pasturage  into  human  food  and  clothing  through  the 
agency  of  their  sheep,  goats,  camels  and  cattle. 

Semple  (9)  has  written  an  excellent  account  of  the  charac- 
teristics of  the  peoples  of  plains,  steppes  and  deserts,  as  com- 
pared with  other  geographic  environments.  We  need  not  judge 
their  qualities  entirely  by  our  own  standards.  They  are  con- 
ceded to  possess  courage  and  hardihood  and  keen  powers  of  ob- 
servation. Their  standards  of  honesty  and  respect  for  property 
rights  depend  on  whether  their  relations  are  with  one  of  their 
own  people  or  with  a  stranger  or  foreigner,  but  this  trait  is  in 
great  measure  the  result  of  their  environment.  David,  the  self- 
reliant  and  brave  youth,  the  great  captain,  and  the  national 
hero  in  whom  all  the  noblest  elements  of  Hebrew  genius  were 
combined,  was  the  product  of  a  shepherd  tribe. 

444.  Diet  an  Important  Factor  in  Determining  the  Physical 


THE  DIETARY  HABITS  OF  MAN  405 

and  Moral  Attributes  of  Peoples. — Students  of  human  history 
have  many  times  attempted  to  discover  the  causes  which  have 
determined  the  peculiar  traits  of  different  peoples,  but  no  gen- 
eral agreement  has  been  reached  as  to  the  relative  importance 
of  racial  stock,  climate  and  geographic  environment  in  deter- 
mining physical,  mental  and  moral  attributes.  Aside  from  a 
small  group  of  sentimental  enthusiasts  who  have  discussed  the 
merits  of  vegetarian  practices  as  contrasted  with  meat  eating, 
largely  on  the  basis  of  whimsical  evidence,  and  moral  considera- 
tions, no  one  has,  however,  attributed  any  great  importance  to 
the  character  of  the  diet,  except  as  regards  abundance  or  scar- 
city of  food,  on  the  character  and  physical  well-being  of  peo- 
ples. I  would  not  detract  in  the  slightest  degree  from  the  im- 
portance of  inherited  characters,  or  of  physical  environment  as 
factors  in  the  formation  of  human  qualities,  but  must  insist  that 
students  of  mankind  have  hitherto  failed  to  realize  the  im-  ) 
portance  of  the  selection  of  the  food  supply  as  an  agency  in  ) 
the  improvement  of  a  race. 

445.  The  Arabs  as  an  Example  of  Excellent  Nutrition. — 
The  people  inhabiting  Central  Asia  domesticated  animals  of  vari- 
ous kinds  from  which  the  domestic  cow,  sheep,  goat,  camel  and 
horse  have  been  developed  through  selection  of  certain  types 
for  breeding.  Much  of  the  country  in  that  part  of  the  world  is 
too  dry  at  times  during  the  summer  to  make  possible  any  rea- 
sonable degree  of  certainty  of  the  outcome  of  the  cultivation 
of  crops,  and  is  to-day  largely  tenanted  by  pastoral  tribes.  It 
was  in  the  semi-arid  regions  of  Asia  that  the  earliest  advances 
toward  achievement  were  made.  We  see  in  certain  of  the  pas- 
toral Arab  tribes  to-day,  people  who  are  living  much  as  have 
their  ancestors  and  those  of  their  neighbors,  for  hundreds  of 
generations.  The  Arabs  are  physically  as  fine  a  people  as  any 
in  the  world.  They  are  singularly  free  from  physical  defects, 
and  present  the  ideal  of  physical  beauty  in  a  remarkable  num- 
ber of  individuals  who  are  not  disfigured  by  the  date  boil  or 
Aleppo  button  which  is  caused  by  an  infection  in  the  face, 
usually  occurring  during  childhood.  They  live  in  a  climate 
which  is  inhospitable  a  large  part  of  the  year  because  of  exces- 
sively high  temperatures.  They  have  contended  with  drought 
and  scanty  pastures  from  time  immemorial,  yet  they  are  a  vig- 
orous and  virile  people.  Deformities  are  very  rare  among  them, 
and  their  children  do  not  suffer  from  skeletal  abnormalities  char- 
acteristic of  rickets  as  do  so  large  a  proportion  of  those  of  Europe 


406     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

and  America.  Not  only  are  the  Arabs  well  developed  and  ath- 
letic, but  they  have  the  courage  to  care  for  their  flocks  and 
herds  under  the  most  trying  conditions.  Actuated  by  the  desire 
to  trade  or  to  carry  on  warfare,  or  stimulated  by  religious  zeal 
to  visit  the  holy  cities  of  the  Mahometans,  they  have  undertaken 
long  and  tiresome  voyages  over  the  parched  deserts.  No  peo- 
ple can  have  such  a  history,  who  have  not  had  a  diet  which 
closely  approached  the  optimal  relations  in  respect  to  all  its 
parts. 

446.  The  Diet  of  the  Pastoral  Arab. — As  would  be  expected, 
the  diet  of  the  pastoral  Arabs  consists  in  great  measure  of  milk, 
supplemented  with  moderate  amounts  of  meat,  cereals  and  dates. 
In  settled  agricultural  districts  pomegranates,  melons  and  a  few 
other  things  enter  regularly  into  the  food  supply.    A  great  pro- 
portion of  the  wealth  of  Arabs  consists  of  flocks  of  sheep  and 
herds  of  goats  and  of  camels.     Cattle  and  horses  are  of  secondary 
importance,  because  they  are  poor  travellers.    The  milk  used  is 
derived  from  goats  and  camels  and  is  mostly  soured  promptly 
and  eaten  as  curds,  because  of  the  impossibility  of  preserving 
in  a  warm  climate  so  perishable  a  food  by  other  means.    Cheese 
and  dried  curds  are  also  staple  articles  of  diet  among  them. 
This  regimen  represents  a  diet  largely  of  a  carnivorous  nature, 
but  supplemented  with  more  or  less  of  vegetable  foods.    It  is 
of  the  greatest  importance  to  these  peoples  that  their  diet  does 
contain  much  milk  for  they  have  little  opportunity  to  eat  of 
the  articles  which  are  suited  for  the  preparation  of  salads  and 
greens.    They  could  not  subsist  upon  a  meat,  cereal  and  fruit 
diet  without  becoming  inferior  physically. 

447.  High  Protein  Diet  Is  Excellent  if  Properly  Selected. — 
The  relative  merits  of  diets  poor  or  rich  in  protein  have  been 
much   discussed.    The  experience  of  the  pastoral   nomads  of 
Arabia  and  other  parts  of  Asia  answer  this  question  very  defi- 
nitely.   A  diet  of  milk  and  meat  with  small  additions  of  veg- 
etable foods  is  very  rich  in  protein  and  it  induces  most  excellent 
development  and  great  longevity.    According  to  the  Encyclo- 
pedia Britannica  (Vol.  2,  p.  285,  llth  Ed.),  "physically  the  Arabs 
are  one  of  the  strongest  and  noblest  races  of  the  world."    Baron 
de  Larrey,  surgeon-general  to  Napoleon  on  his  expedition  to 
Egypt  and  Syria,  wrote:    "Their  physical  structure  is  in  all 
respects  more  perfect  than  that  of  Europeans;  their  organs  of 
sense  are  exquisitely  acute,  their  size  above  the  average  of  men 
in  general,  their  figure  robust  and  elegant,  their  color  brown; 


THE  DIETARY  HABITS  OF  MAN  407 

their  intelligence  proportionate  to  their  physical  perfection,  and 
without  doubt  superior,  other  things  being  equal,  to  that  of  other 
nations."  In  the  same  article  it  is  further  stated  of  the  Arabs 
that  "Simple  and  abstemious  in  their  habits  they  often  reach 
an  extreme  yet  healthy  old  age;  nor  is  it  common  among  them 
for  the  faculties  of  the  mind  to  give  way  sooner  than  those  of 
the  body." 

The  use  of  very  liberal  amounts  of  milk  is  the  rule  among 
the  peoples  of  Northern  Africa,  Arabia,  Mesopotamia,  the  Bal- 
kan States  and  throughout  wide  areas  in  Asia.  Wherever  dairy 
animals  are  abundant  in  proportion  to  the  population,  fine  physi- 
cal development  is  seen  without  exception. 

448.  McKay's  Observations  on  the  Diet  and  Physical  Effi- 
ciency of  Hindu  Peoples. — McKay  (3)  has  described  the  physi- 
cal condition  of  the  habitants  of  different  parts  of  India,  and 
correlated  this  with  the  character  of  their  diets.  His  observa- 
tions leave  no  room  for  doubt  that  the  pastoral  tribes  are  vastly 
superior  in  strength  and  health  and  manly  qualities  generally, 
to  other  classes  of  Indians.  In  those  parts  of  India  where  the 
diet  is  largely  derived  from  cereals  the  physical  development  of 
the  people  appears  to  be  poorest.  The  rice  eaters  of  Bengal 
are  the  most  extreme  example.  The  details  regarding  the  com- 
ponents of  the  diets  of  the  different  classes  studied  by  McKay 
are  not  sufficiently  complete  to  serve  our  present  purpose  as 
well  as  we  would  wish,  for  he  was  interested  primarily  in  the 
amount  of  protein  which  the  different  diets  supplied.  At  the 
time  his  book  was  written,  it  had  been  hastily  concluded  by 
investigators  that  science  had  revealed  all  the  facts  necessary 
for  the  rational  control  of  diet,  and  that  it  remained  merely  to 
determine  certain  minor  principles  which  could  contribute  to 
physiological  well-being.  It  was  not  deemed  of  importance  in 
his  elaborate  investigation,  therefore,  to  list  the  individual  food- 
stuffs eaten  and  their  quantitative  relations.  To-day  this  is 
regarded  as  the  most  essential  thing  to  know,  when  we  are  called 
upon  to  evaluate  a  dietary  regimen.  McKay's  studies,  based 
upon  personal  observations,  and  on  the  reports  of  officers  of  the 
British  Army  to  their  Government  concerning  the  fitness  of  the 
men  in  different  parts  of  India  for  military  service,  forms  one 
of  the  strongest  confirmations  of  the  applicability  of  the  prin- 
ciples of  nutrition  discussed  in  this  book  to  human  experience. 

The  sour  milks  used  so  extensively  throughout  the  East  are 
variously  designated  sheneena,  leben,  yohourt,  keffir,  koumiss, 


408     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

matzoon  and  dadhi,  and  are  derived  from  milk  of  goats,  camels, 
sheep,  cows  or  mares.  The  fermentation  is  not  purely  a  lactic 
acid  formation  through  transformation  of  the  milk  sugar,  but 
includes  an  alcoholic  fermentation  as  well.  All  these  sour  milks 
contain  not  only  a  relatively  high  acidity  due  to  lactic  acid,  but 
more  or  less  alcohol  as  well. 

449.  Relation  of  the  Consumption  of  Dairy  Products  to 
Health  in  Parts  of  Europe. — We  can  draw  another  parallel  be- 
tween large  groups  of  people  who  show  very  marked  differences 
in  physical  development,  due,  we  believe,  primarily  to  the  dif- 
ferences in  the  quality  of  their  diets.     In  Sweden  in  1900  there 
was  approximately  one  dairy  cow  to  every  two  inhabitants.    A 
similar  relation  is  held  in  Switzerland  with  respect  to  the  develop- 
ment of  the  dairy  industry  in  relation  to  population.    On  the 
other  hand  the  Southern  United  States  had  but  one  cow  to  five 
to  ten  or  more  people.    There  are  no  places  in  Europe  where 
more  hardy  and  aggressive  men  and  women  are  to  be  found 
than  in  Scandinavia  and  in  Switzerland.    In  marked  contrast 
stand  health  conditions  in  the  Southern  States,  as  is  shown, 
among  other  ways,  in  the  high  incidence  of  pellagra,  which  Gold- 
berger  has  demonstrated,  is  directly  attributable  to  inadequate 
diet.    Like  many  other  lines  of  evidence,  we  cannot  push  too 
far  our  contrasts  of  this  character,  because  other  factors  can  be 
readily  suggested  to  account  in  a  satisfactory  manner  for  ob- 
served facts.    Human  subjects  do  not  as  a  rule  restrict  them- 
selves to  one-sided  diets  to  a  degree  which  leads  to  unequivocal 
and  extreme  conditions  corresponding  with  the  results  of  animal 
experimentation.    The  parallels  which  we  have  drawn,  do,  how- 
ever, correlate  so  well  with  the  results  of  studies  on  animals  as 
to  leave  little  room  for  denial  of  their  justification. 

450.  Huratington's  Views-  on  the  Effects  of  Climate  on  Man. 
— Huntington  believes  that  climate  is  the  most  important  factor 
in  determining  the  development  of  a  highly  progressive  race  or 
nation.    As  a  result  of  his  studies  he  concludes  that  a  mean 
temperature  of  64°  F.,  a  mean  humidity  of  about  80  per  cent, 
and  frequent  changes  of  temperature  are  the  most  desirable  con- 
ditions for  physical  work.    Statistical  evidence  is  offered  to  sup- 
port the  theory  that  only  people  who  live  under  conditions  of 
relative  storminess  become  industrious,  capable  and  successful. 
His  evidence  is  very  convincing,  yet  as  I  read  his  books  (8)  on 
Civilization  and  Climate,  and  World  Power  and  Evolution,  I 
could  not  help  forming  the  conclusion  that  while  climate  is  un- 


THE  DIETARY  HABITS  OF  MAN  409 

doubtedly  a  factor  of  great  importance  in  determining  well- 
being  and  consequent  achievement,  the  author  had  ignored  facts 
which  modern  research  has  brought  to  light  in  the  field  of  nutri- 
tion, which  should  find  a  place  in  any  discussion  of  human 
geography. 

451.  Contrast  of  the  Achievement  of  the  People  of  Canada 
and  Those  of  the  Bahamas. — We  have  already  discussed  the 
widespread  occurrence  of  pellagra  in  the  Southern  States,  and 
the  apparently  conclusive  evidence  that  it  is  a  disease  of  the 
poorly  fed.    Let  us  examine  a  contrast  made  by  Huntington  of 
the  virility  of  the  Canadians  and  the  improvident,  lazy  natives 
of  the  Bahamas.     It  is  stated  that  at  the  time  of  the  Revolu- 
tion certain  Loyalists  in  the  Northern  States  preferred  to  emi- 
grate to  Canada  rather  than  live  under  the  Stars  and  Stripes. 
Other  Loyalists  in  the  South  betook  themselves  to  the  inviting 
climate  of  the  Bahamas  for  a  like  reason.    We  will  all  agree 
that  their  ancestors  were  equally  capable  and  aggressive,  although 
of  very  different  mental  types.    The  former  are,  it  is  pointed 
out,  an  industrious,  educated  and  progressive  people,  whereas 
the  latter  are  indolent  and  unprogressive,  having  suffered  retro- 
gression since  their  settlement  in  the  islands.    The  explanation 
offered  for  this  great  difference  in  quality  of  the  two  groups  to- 
day, is  that  the  climate  of  Lower  Canada  is  a  highly  stimulating 
one,  whereas  that  of  the  Bahamas  is  too  mild  and  uniform. 

While  at  first  thought  it  seems  logical  to  attribute  the  differ- 
ences in  stamina  and  aggressiveness  of  the  Canadians  and  the 
people  of  the  Bahamas  to  climate,  there  are  now  good  reasons 
why  we  should  consider  other  possible  factors,  notably  the  char- 
acter of  the  diets  of  these  two  groups  of  people  as  a  factor  con- 
tributing to  the  success  of  the  former  and  to  the  failure  of  the 
latter.  Before  discussing  these  differences  it  will  be  well  to 
consider  in  some  detail  the  part  which  may  be  played  by  climate 
and  by  diet  on  the  physiological  well-being  of  man.  We  shall, 
therefore,  return  again  later  to  the  part  which  the  character  of 
the  food  supply  of  these  two  geographically  different  regions  has 
probably  played  in  determining  the  attitude  of  their  peoples 
toward  life  and  work. 

452.  Most  People  Are  Unwell. — No  one  will  be  likely  to 
dispute  the  statement  that  most  people  are  unwell,  and  that 
their  failures,  indiscretions,  fits  of  temper,  tendency  to  com- 
plain, tendency  to  give  themselves  up  to  reflecting  on  the  pos- 
sibilities for  everything  going  wrong,  their  lack  of  enthusiasm 


410     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

and  other  qualities  which  contribute  to  making  them  unhappy 
and  inefficient  creatures,  are  in  great  measure  the  result  of  ill 
health.  We  must  grant  that  hereditary  mental  defects  are  wide- 
spread and  are  inherited  as  are  other  mental  tendencies,  but 
who  can  say  how  frequently  the  confirmed  grouch  is  not  what  he 
is  because  of  disturbances  in  his  meTatyoilF"processes.  The  pee- 
vishness and  unreasonableness  of  persons  convalescing  from  seri- 
ous diseases  is  a  matter  of  common  knowledge.  Intolerance 
tends  to  develop  in  those  who  are  continually  in  low  spirits,  and 
there  can  be  no  reasonable  doubt  that  the  diet  may  deviate  from 
the  optimal  even  in  the  United  States,  to  a  degree  which  can 
easily  cause  the  results  we  see.  It  has  produced  comparable 
effects  in  our  rat  colony,  when  the  choice  of  food  was  entirely 
comparable  to  human  experience  here. 

Under  faulty  nutrition  the  machinery  of  the  body  tends  to 
break  down  in  places  and  with  frequency.  The  exact  nature  of 
the  defects  which  develop  cannot  in  general  be  traced  to  their 
ultimate  causes.  Chemistry  and  histology  have  now  made  it 
clear  that  the  functions  of  living  matter  depend  solely  upon  the 
chemical  complexes  contained  therein,  and  especially  on  the 
structure  or  organization,  of  its  components.  Its  peculiar  prop- 
erties depend  upon  its  structure.  This  is  not  homogeneous,  but 
affords  a  wide  variety  of  types  which  are  revealed  by  histologi- 
cal  methods.  It  is  the  minute  structure  of  the  protoplasm  which 
suffers  change  when  the  nutritive  conditions  deviate  from  the 
optimal,  and  the  result  is  faulty  operation  and  an  abnormal 
human  being  or  animal.  We  have  become  well  aware  how  very 
slight  changes  in  the  chemical  or  physical  conditions  may  make 
pronounced  differences  in  the  properties  of  emulsions  or  of  col- 
loidal solutions.  It  has  been  demonstrated  in  our  study  of  the 
effects  of  varying  the  ratios  between  calcium  and  phosphate  in 
the  diet  on  the  histological  picture  of  the  bones,  that  equally 
small  deviations  from  the  optimal  composition  of  the  food  may 
in  certain  cases,  produce  profound  changes  in  the  manner  of 
organization  of  the  finer  structures  of  the  living  tissues.  Func- 
tion, too,  has  been  shown  to  deviate  to  a  degree  comparable  with 
the  histological  changes. 

453.  The  Most  Stimulating  Climates  Are  Not  Promoting 
Health  in  Man  More  Than  Less  Stimulating  Ones. — If  climate 
were  responsible  for  health  to  the  degree  that  its  enthusiasts 
believe,  how  are  we  to  account  for  the  amount  of  sickness,  early 
aging  and  physical  inefficiency  seen  in  the  most  favorable  cli- 


THE  DIETARY  HABITS  OF  MAN  411 

matic  areas,  such  as  the  northeastern  quarter  of  the  United 
States  and  England,  and  the  fine  physical  development  of  the 
Arabs  and  the  pastoral  tribes  of  Asia,  whose  climate  is  less 
stimulating?  The  teeth  of  the  Americans  and  English  of  the 
present  generation  are  indescribably  bad,  even  where  the  climate 
is  held  to  be  best  adapted  to  health,  and  to  the  promotion  of 
physical  and  mental  activity.  What  stands  in  the  way  of  prog- 
ress of  Asiatic  and  African  peoples  which  has  kept  them  far 
behind  the  Europeans  and  Americans  in  advancing  learning?  It 
seems  more  plausible  to  regard  the  failure  of  certain  peoples  to 
progress  as  primarily  a  geographic  one  quite  as  much  as  cli- 
matic. The  nature  of  the  land,  and  its  rainfall  determine  the 
character  and  vigor  of  the  vegetation,  and  indirectly  the  char- 
acter of  the  diet.  Climate  determines  the  kind  of  agriculture 
which  is  profitable,  and,  therefore,  the  most  satisfactory  mode  of 
life  of  the  people  of  any  region.  Conditions  of  living  are  often 
so  hard  that  the  vitality  of  every  individual  is  taxed  to  the 
utmost  to  secure  the  primary  physical  needs  for  food,  clothing 
and  shelter.  In  the  case  of  the  herdsman  his  constant  activity 
in  the  open  denies  him  the  opportunity  to  invent  machinery  or 
to  develop  experimental  sciences.  He  never  feels  the  need  for 
these,  because  of  his  mode  of  life.  Climate  does  not  necessarily 
prevent  his  advance,  except  indirectly  through  determining  his 
mode  of  life  and  the  things  upon  which  he  will  fix  his  thoughts. 
There  is  little  prospect  that  an  arid  region  can  be  utilized  in 
any  other  manner  than  through  raising  animals  on  its  scanty 
pasturage,  so  it  seems  impracticable  to  attempt  to  make  any- 
thing out  of  such  places  except  what  they  are.  It  is,  however, 
quite  another  matter  when  we  turn  to  tropical  regions,  with  their 
unlimited  possibilities  for  agriculture.  Are  we  to  accept  the 
gloomy  picture  which  Huntington  draws  for  us  of  the  utter 
hopelessness  of  making  the  tropics  the  abode  of  human  culture? 
I  am  not  convinced  that  this  problem  is  an  insolvable  one.  . 

454.  Plant  and  Animal  Enemies  in  the  Tropics  Are  More  ** 
Serious  Than  Climate. — Are  not  the  real  enemies  to  human  life 
and  happiness  in  the  Torrid  Zone,  plants  and  animals  rather 
than  temperature  and  humidity?  If  this  is  admitted,  no  one 
who  is  imbued  with  the  spirit  of  modern  science,  would  seriously 
doubt  that  the  improvement  of  conditions  of  living  and  of  man 
himself  in  the  warmer  parts  of  the  world  is  possible  provided  the 
solution  of  the  problems  is  attempted  in  the  right  manner.  As 
for  the  animal  enemies  the  scientist  will  ask  those  who  may 


412     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

give  him  information:  What  are  the  peculiar  habits  of  each 
species  which  we  desire  to  rid  ourselves  of?  What  is  their  food 
and  what  is  the  history  of  their  reproduction?  Has  each  of 
them  any  natural  enemies  either  animal  or  bacterial  or  fungal? 
When  he  has  secured  such  information  as  is  available,  he  sets 
himself  to  study  in  the  minutest  detail,  every  character  which 
may  enable  him  to  overcome  his  enemy  whether  it  be  a  serpent, 
worm  or  insect,  and  ultimately,  as  the  result  of  the  accumulation 
of  data  which  seems  dry  and  uninteresting  to  anyone  but  the 
specialist,  he  is  able  to  control  the  pest  or  to  exterminate  it. 
When  the  human  mind  of  a  certain  type  is  freed  from  inter- 
ference, and  is  given  resources,  and  a  specific  problem  to  solve, 
the  result  is  practically  a  certainty. 

When  we  turn  to  plant  enemies,  we  find  the  tropics  filled  with 
them.  Conditions  for  vegetable  growth  are  so  favorable  that 
human  strength  cannot  cope  with  them.  But  nowadays  we  do 
not  regard  it  as  necessary  to  struggle  by  means  of  living  flesh 
with  the  weeds  which  seek  to  choke  our  useful  plants.  We  har- 
ness and  direct  the  forces  of  nature.  There  are  abundant  sources 
of  energy  available  to  relieve  mankind  entirely  of  the  necessity 
of  laboring  with  his  hands.  The  energy  of  mountain  torrents, 
of  most  of  the  large  and  small  rivers,  of  the  tides,  of  the  winds, 
and  of  sunlight,  are  as  yet  very  little  utilized  because  the  stores 
of  fossil  plant  tissues  in  the  form  of  coal  have  made  it  cheaper 
to  use  it  prodigally  rather  than  seek  to  compete  with  this  source 
of  energy  in  other  directions.  But  who  is  so  faint-hearted  as  to 
think  that  it  cannot  be  that  energy  will  be  made  available  to 
turn  the  soil  as  often  and  work  it  as  thoroughly  as  is  necessary 
in  order  to  eradicate  the  dragon  of  vegetable  growth  which  dis- 
courages the  would-be  farmer  of  the  tropics?  I  can  see  no  great 
difficulty  in  the  use  of  numbers  of  large  lenses,  cheap  and  rela- 
tively imperfect,  for  concentrating  the  sun's  rays  to  several  times 
their  existing  dispersal,  and  thus  creating  temperatures  sufficient 
to  destroy  all  existing  vegetation  over  the  area  so  treated,  and 
within  a  very  short  space  of  time,  and  very  little  human  effort. 
With  the  destruction  of  plants  in  the  axils  of  which  water  con- 
stantly exists,  the  mosquitoes  which  come  from  these  receptacles 
would  disappear. 

Just  suppose  we  were  able  to  successfully  cope  with  our  ani- 
mal and  vegetable  enemies  in  the  tropics,  and  that  the  soil  were 
made  to  yield  the  great  return  of  useful  produce  of  which  it  is 
capable.  Suppose  that  the  diseases  which  harass  and  destroy 


THE  DIETARY  HABITS  OF  MAN  413 

domestic  animals  and  which  undermine  the  health  of  man  were 
eradicated.  Suppose  this  were  accomplished  and  mechanical 
energy  were  made  available  sufficient  to  perform  all  the  neces- 
sary labor  of  agriculture,  and  of  manufacturing  processes. 
Would  there  then  stand  anything  in  the  way  of  developing  in  the 
less  hospitable  parts  of  the  warm  regions  of  the  world,  a  credit- 
able civilized  society?  We  should  certainly  not  be  despondent 
over  the  task  until  it  has  been  tried. 

455.  Under  What  Conditions  Does  Man  Tend  to  Develop 
Best  Intellectually? — One  not  infrequently  sees  in  discussions 
of  this  nature  the  statement  that  in  warm  regions,  where  food 
is  easily  obtainable,  and  little  shelter  or  clothing  is  necessary 
for  the  comfort  of  man,  he  sinks  into  indolence,  and  remains  in 
a  state  of  ignorance  and  degeneracy.  It  is  urged  that  only  in 
such  a  climate  as  necessitates  exertion  and  foresight  during  the 
summer  in  order  to  provide  food,  shelter  and  clothing  with  which 
to  pass  a  severe  winter  in  comfort,  will  man  develop  in  a  satis- 
factory way  the  higher  virtues  of  civilization.  The  theory  has 
been  postulated  that  energy,  aggressiveness,  frugality,  foresight, 
inventiveness,  solicitude  for  dependents,  respect  for  property 
rights  and  other  virtues  of  man  in  his  most  highly  advanced  con- 
dition, are  best  fostered  in  a  climate  that  offers  vicissitudes,  and 
requires  that  the  life  of  the  individual  shall  be  a  struggle  with 
his  environment. 

Others  tell  us,  and  it  appears  logical,  that  as  long  as  man  is 
forced  to  spend  his  days  in  a  struggle  for  existence  he  cannot 
develop  his  higher  mental  qualities.  It  is  said  that  the  creation 
of  an  aristocratic  element  in  society,  whose  wants  are  supplied 
by  the  labor  and  sacrifice  of  a  less  fortunate  group,  establishes 
the  ideal  condition  for  fostering  the  mental  growth  that  comes 
from  reflection  and  the  study  of  the  ideas  of  others. 

There  is  doubtless  an  element  of  truth  in  each  of  these  views 
regarding  the  conditions  under  which  man  will  best  develop  his 
mental  capacities.  Leisure  is  essential  to  certain  types  of  cre- 
ative thought.  Thought  is  stimulated  profoundly  through  dis- 
cussion, reading  and  observation  of  the  phenomena  of  nature. 
It  is  not  yet  demonstrated,  however,  that  such  creative  thought 
is  possible  or  probable  only  in  temperate  regions  where  there  are 
frequent  and  pronounced  changes  in  temperature.  One  of  the 
conditions  of  progress  is  hopefulness  and  a  realization  of  one's 
powers.  In  temperate  regions  the  problems  of  life  are  less 
difficult  to  solve  than  they  are  in  the  tropics.  The  winters  de- 


414     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

stroy,  or  prevent  the  invasion  of  many  forms  of  insect  life  which 
go  unhampered  in  tropical  climes.  The  cattle  tick  and  the 
Tsetse-fly,  which  bear  respectively  the  Texas  fever  and  the  sleep- 
ing sickness  do  not  survive  the  northern  winters,  and  the  popu- 
lation of  these  regions  enjoy  freedom  from  these  diseases.  Cold 
winters  limit  the  number  of  species  of  weeds  and  other  noxious 
plants,  and  render  the  production  of  useful  crops  less  laborious. 
These  are  factors  of  the  greatest  importance  to  agriculture  and 
to  the  welfare  of  man.  In  the  tropics  the  problems  set  for 
solution  before  the  mind  of  man  have  been  of  greater  magnitude 
and  more  difficult  to  solve.  Accordingly  the  natives  have  not 
only  not  solved  them,  but  have  become  crushed  by  them.  They 
have  suffered  from  lack  of  power  to  overcome  their  enemies,  and 
have  been  forced  to  live  the  lives  of  fugitives  in  the  more  favored 
nooks  where  nature  made  conditions  less  disheartening.  Jin  order 
that  he  may  progress,  man  must  not  be  faced  by  insuperable  dif- 
ficulties. He  must  gain  his  confidence  and  his  mastery  over  the 
forces  of  nature  in  the  more  favorable  parts  of  the  world.  From 
these  points  of  vantage,  confident  of  his  powers,  he  will  through 
the  work  of  that  most  valuable,  although  numerically  very  small 
element  in  the  population,  the  laboratory  investigators,  acquire 
the  necessary  knowledge,  then  lay  his  plans  for  the  conquest  of 
one  of  Nature's  greatest  prizes,  the  tropics. 

456.  Of  All  Factors  Diet  Is  the  Most  Important  in  Deter- 
mining How  One  Feels. — The  most  fundamental  of  all  the  fac- 
tors which  contribute  to  success  in  any  enterprise  is  health,  and 
the  primary  factor  in  making  a  faultless  organism,  either  human 
or  animal,  is  the  diet.  It  is  not  permissible  to  attribute  the  dif- 
ferences observed  between  the  Bahamans  and  Canadians  solely 
to  climate,  for  their  diet  has  been  so  different  that  there  is  good 
reason  to  suspect  that  the  attitude  toward  work  and  mental 
effort  in  the  two  groups  is  in  no  small  measure  due  to  the  way 
they  feel.  Our  knowledge  of  the  effects  of  an  unsatisfactorily 
constituted  diet,  warrants  us  in  attributing  their  characteristics 
to  this  cause.  The  Bahamas  produce  tamarinds,  olives,  lemons, 
oranges,  limes,  citrons,  pineapples,  pomegranates,  figs,  sapodillas, 
bananas,  melons,  yams,  potatoes,  cucumbers,  cassiva,  sugar, 
maize  and  peas  as  the  chief  edible  articles.  From  what  has  been 
said  this  list  of  storage  tissues  of  plants  is  not  likely  to  promote 
health.  Their  bread-stuff  and  meats  are  imported  from  the 
United  States.  The  people  of  Lower  Canada  have,  on  the  other 
hand,  a  diet  much  like  that  of  the  United  States,  viz.:  one  into 


THE  DIETARY  HABITS  OF  MAN  415 

which  a  considerable  amount  of  dairy  products  enters  regularly. 
It  consists  principally  of  cereals,  legume  seeds,  tubers  and  meats, 
but  milk,  butter,  cheese  and  cream  are  regular  components. 
People  will  feel  very  differently  on  these  two  types  of  diet. 

457.  Differences  in  Labor  Output  Observed  by  Huntington 
in  North  and  South  May  Have  Been  in  Part  Due  to  Causes 
Other  Than  Climate. — It  is  scarcely  permissible  to  compare 
the  work  accomplished  by  natives  of  Tampa  with  that  of  workers 
in  the  northern  states  as  Huntington  has  done  in  his  studies  on 
the  effect  of  climate,  because  most  of  the  men  in  Tampa  are 
infected  with  hookworm,  and  many  have  or  have  had  malaria, 
conditions  from  which  the  northerners  are  free.    The  southern 
group  would  also  tend  to  live  on  the  type  of  diet  so  common 
among  the  working  classes  of  the  South,  and  which  has  been 
shown  to  predispose  to,  if  it  does  not  actually  cause  pellagra. 
We  should  expect  the  southern  group  of  workers  to  feel  less  like 
working  than  the  northern  one,  entirely  aside  from  climatic  fac- 
tors, because  of  the  less  satisfactory  character  of  their  food 
supply. 

458.  Bad  Health  Conditions  in  the  United  States  Notwith- 
standing Its  Stimulating  Climate. — Let  us  return  to  the  prob- 
lem of  the  health  conditions  among  the  people  of  the  northern 
United  States  and  its  causes.    We  are  told  by  Terman  (10)  that 
about  fourteen  million  of  the  twenty  million  school  children  in 
the  United  States  are  handicapped  by  some  kind  of  physical 
defect,  and  that  not  far  from  two  million  are  suffering  from  a 
grave   form  of  malnutrition.      Ten  million   are   said  to   have 
enough  defective  teeth  to  seriously  interfere  with  health,  and  as 
many  are  infected  with  tuberculosis,  and  he  estimates  that  two 
million  will  eventually  die  of  this  disease.    One  million   are 
stated  to  be  predisposed  to  some  serious  form  of  nervous  dis- 
order.   That  the  conditions  are  fully  as  bad  as  these  figures 
indicate  is  borne  out  by  the  results  of  medical  examination  of 
young  men  for  the  draft  in  the  Great  War.    Why  this  condition 
in  our  boasted  favorable  climate  for  civilization,  whereas  the 
pastoral  tribes  of  Asia,  the  nomads  of  the  desert,  and  the  peo- 
ples of  the  Balkan  States  have  no  such  physical  handicaps?    It 
certainly  behooves  us  to  seek  to  discover  the  cause  or  causes 
which  are  responsible  for  this  condition.     Climate  has  had  its 
opportunity  and  has  not  saved  us  from  our  unenviable  physical 
and  health  standards.     As  a  result  of  my  many  experimental 
observations,  I  have  come  to  hold  the  view  that  animal  experi- 


416      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

mentation,  human  geography  and  history,  all  point  in  an  all  but 
conclusive  manner  to  the  diet  as  the  principal  cause  of  our  health 
troubles,  in  so  far  as  these  are  not  brought  about  by  commu- 
nicable diseases. 

459.  Changes  in  the  Character  of  the  American  Diet  Dur- 
ing Recent  Decades. — There  have  been  in  course  of  development 
during  the  last  century,  changes  in  the  character  of  the  diet  of 
the  greater  portion  of  the  inhabitants  of  the  United  States  which 
were  never  suspected  as  of  any  moment  from  the  standpoint  of 
health  until  their  significance  was  brought  to  light  by  laboratory 
investigations  in  nutrition  during  the  last  six  years.    Of  these, 
probably  the  most  important  because  so  insidious,  is  the  great 
extension  of  the  consumption  of  cereal  grains,  and  the  changes 
in  the  process  of  preparing  these  for  human  food. 

460.  The  Cereal  Grains  as  a  Menace  to  Health, — The  results 
of  our  investigations  on  the  nutritive  value  of  the  cereal  grains 
disturbed  a  well  established  belief  that  these  were  highly  satis- 
factory foods.     When  investigated  by  adequate  methods  they 
proved  to  be  deficient  in  the  amount  and  quality  of  their  pro- 
teins, in  certain  mineral  elements,  and  in  two  of  the  well  dem- 
onstrated vitamins.    Since  all  experimental  results  should  tally 
with  human  experience  it  was  natural  that  we  should  reflect 
upon  the  extent  to  which  these  incomplete  foods  enter  into  the 
human  diet,  and  whether  man  has  throughout  long  periods  of 
his  history,  taken  amounts  comparable  to  what  he  does  to-day. 
Any  changes  from  long  established  usage  in  this  matter  should, 
we  believed,  be  given  careful  consideration  to  see  whether  a 
course  is  being  pursued  which  may  place  our  health  standards 
in  jeopardy.    There  appears  to  be,  in  fact,  a  use  of  this  class 
of  foods  to  an  extent  which  was  never  before  practiced,  and  which 
has  considerably  exceeded  the  limit  of  safety. 

Primitive  man  ate  everything  he  could  secure  which  was  edible. 
His  animal  food  included  the  flesh  of  such  animals  as  he  could 
catch,  and  also  fish,  eggs,  birds,  shell-fish,  insects,  etc.  Among 
the  vegetable  products  which  he  doubtless  ate  were  fruits,  ber- 
ries, fleshy  roots,  nuts  and  a  few  other  seeds  of  plants,  among 
which  were  the  seeds  of  those  grasses  which  have  since  been 
developed  into  our  cereal  crops.  There  are  relatively  few  re- 
gions where  nuts  are  sufficiently  abundant  to  furnish  a  regular 
article  of  diet  for  a  sparse  population  during  even  a  few  months 
of  the  year.  The  supply  of  cereal  grains  was  even  more  inade- 
quate. The  cereal  grains  are  the  seeds  of  several  grasses.  In  a 


THE  DIETARY  HABITS  OF  MAN  417 

country  where  no  agriculture  was  practiced,  grasses  would  be 
cropped  by  grazing  animals  and  the  development  of  seed  would 
be  greatly  interfered  with.  As  Huntington  points  out  (8) 
extensive  agriculture  was  impossible  until  after  animals  were 
domesticated.  Such  seed  as  was  produced  was  borne  on  isolated 
and  scattered  stems  and  would  be  difficult  to  harvest  in  appre- 
ciable quantities.  One  exception  was  the  wild  rice  plant  which 
grew  in  the  water  and  was  protected  to  some  extent  from  ani- 
mals. It  was  more  abundant  in  certain  places  than  the  seeds 
of  any  land  grasses  were  likely  to  be  in  the  unmolested  fruiting 
condition.  Rice  was  harvested,  therefore,  from  very  early  times 
in  parts  of  Asia  and  in  some  of  the  northern  states  of  North 
America.  Even  in  these  favored  regions  of  shallow  lakes  and 
rivers,  however,  rice  never  formed  a  principal  component  of  the 
diet  of  the  Indians,  but  only  an  adjutant  in  the  fall  and  early 
winter.  Grass  seeds  of  the  type  of  the  cereal  grains  are  always 
eagerly  sought  for  at  ripening  by  birds,  and  the  harvest  time 
would  always  be  short.  Maize  was  never  a  food  of  much  im- 
portance among  the  Indians  but  served  only  to  vary  their  other- 
wise carnivorous  diet.  All  the  higher  apes  eat  more  or  less  of 
the  tender  leaves  which  have  mild  flavors.  After  man  reached 
the  stage  of  development  where  food  was  regularly  cooked,  he 
was  able  to  eat  coarse  vegetables  of  the  leafy  type  in  greater 
variety  and  in  larger  amounts  than  when  he  had  to  eat  them 
raw,  because  of  the  difficulty  of  digesting  some  of  them.  Pot- 
herbs early  became  a  regular  part  of  the  food  of  human  beings 
as  they  advanced  toward  civilization.  They  are  to-day  the  out- 
standing feature  of  the  diet  of  the  Chinese  and  Japanese. 

461.  Great  Extension  in  the  Cultivation  of  Cereals  in  Recent 
Times. — The  great  increase  in  the  consumption  of  cereal  grains 
in  various  forms  as  flours,  cornmeal,  corn  grits,  rolled  oats  and 
the  breakfast  foods  with  which  we  are  familiar,  is  an  incident 
in  the  development  of  modern  industry,  and  in  the  change  from 
a  rural  to  an  urban  life.  This  has  forced  a  great  part  of  the 
population  to  depend  upon  the  remainder  for  food,  and  the  result 
has  been  the  cultivation  in  ever  increasing  amounts  of  those 
farm  crops  which  yield  the  greatest  returns  in  the  food  sub- 
stances which  were  deemed  of  greatest  importance,  viz.:  energy 
and  protein  values.  For  many  years  preceding  the  recent  dis- 
coveries regarding  food  values,  the  U.  S.  Department  of  Agri- 
culture published  numerous  bulletins  containing  the  advice  to 
the  housewife  to  spend  a  large  part  of  every  dollar  invested  in 


418      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

food  for  wheat  flour  and  other  milled  cereal  products,  and 
vegetable  fats,  because  these  were  the  purchases  by  which  she 
could  secure  the  greatest  amounts  of  protein  and  energy.  With 
each  succeeding  decade  the  acreage  of  the  entire  world  which 
was  devoted  to  the  cultivation  of  cereal  grains  has  been  enor- 
mously increased  for  a  century. 

In  great  measure  this  was  due  to  the  invention  of  machinery 
which  made  possible  the  tilling  of  the  soil  and  the  harvesting  and 
threshing  of  grain  with  a  minimum  expenditure  of  human  labor. 
Furthermore,  this  type  of  agriculture  in  which  the  products  of  the 
soil  and  consequently  its  fertility  were  sold  and  transported  from 
the  farm  year  by  year,  yields  the  greatest  profits  in  areas  too  far 
removed  from  the  city  to  be  successfully  utilized  for  truck 
farming.  The  result  has  been  an  ever  increasing  consumption  of 
cereal  foods.  This  process  was  so  gradual  that  to-day  many 
who  are  fairly  well  versed  in  the  principles  of  nutrition  believe 
that  cereals  are  and  were  from  the  dawn  of  history  the  most 
prominent  and  satisfactory  source  of  human  nutriment.  Actually 
this  is  far  from  true. 

462.  Grass  as  an  Enemy  to  Agriculture. — Huntington  (8) 
has  pointed  out  that  the  great  enemy  of  agriculture  has  always 
been  grass.  Primitive  man  could  never  compete  with  it,  and 
accordingly  could  not  practice  extensively  the  cultivation  of  the 
plants  which  are  now  our  staple  crops.  The  clam  shell  or  the 
crooked  stick  were  ineffective  armament  indeed  for  the  early 
agriculturist.  When  draught  animals  were  domesticated  he  be- 
came capable  of  eradicating  grass,  but  then  the  great  labor 
involved  in  harvesting  and  threshing  cereals  made  their  cultiva- 
tion on  a  large  scale  difficult.  Cereal  grains  were  even  up  to 
comparatively  recent  times  grown  because  of  their  keeping  quali- 
ties, for  in  a  dry  state  they  can  be  preserved  without  deteriora- 
tion for  months  or  years.  They  served  as  a  reserve  food  supply 
to  be  drawn  upon  during  the  less  hospitable  parts  of  the  year,  or 
as  a  safeguard  against  famine  in  lean  years  which  experience 
showed  were  likely  to  occur.  Far-sighted  man  doubtless  adopted 
in  some  measure,  throughout  human  history,  the  practice  of 
hoarding  grain  as  did  Joseph  in  his  management  of  the  business 
of  Pharaoh.  During  the  fat  years  people  subsisted  in  great 
measure  on  the  products  of  the  kine  and  other  animals  which 
were  profitable  for  the  herdsmen.  The  consumption  of  cereal 
grains  to  the  extent  of  35-45  per  cent  of  the  food  supply  as  is 
now  the  rule  in  parts  of  Europe  and  America  constitutes  an 


THE  DIETARY  HABITS  OF  MAN  419 

innovation  in  human  experience,  and  there  are  two  kinds  of 
evidence  available  in  abundance,  which  point  definitely  and 
unmistakably  to  the  belief  that  we  have  already  exceeded  the 
limit  of  safety  in  the  use  of  cereals,  unless  careful  attention  is 
given  to  the  choice  of  the  remainder  of  the  food  supply.  This 
is  necessary  in  order  that  the  deficiencies  of  the  milled  grains 
which  we  use  so  freely  may  be  corrected. 

463.  Evidences  That  We  Have  Exceeded  the  Limits  of 
Safety  in  the  Consumption  of  Cereals. — The  two  kinds  of  evi- 
dence that  we  are  now  exceeding  the  limits  of  safety  in  the  con- 
sumption of  cereal  products  (because  of  the  nature  of  the  re- 
mainder of  the  food  supply)  are:  (1),  the  overwhelming  evidence 
of  the  debilitating  effects  on  animals  of  such  diets  as  are  now  in 
common  use  by  many  families,  and  in  some  measure  by  Euro- 
pean and  American  peoples  generally,  viz.,  the  white  bread,  meat 
and  potato  type  of  diet.    Other  milled  cereal  products  have,  it 
will  be  remembered,  essentially  the  same  dietary  properties  as 
bolted  flour;  (2),  the  great  increase  in  the  incidence  and  severity 
of  certain  physical  defects  in  man  in  recent  times,  the  principal 
features  of  which  are  easily  reproducible  in  animals  by  defective 
diets.    We  need  only  mention  retardation  of  growth  in  children, 
faulty  posture,  tendency  to  nervousness  and  irritability,  defective 
teeth,  and  faulty  skeletal  development.    All  of  these  and  others 
are  now  clearly  recognized  as  national  health  problems  in  the 
United  States  and  other  countries.    It  is  one  of  the  great  triumphs 
of  scientific  investigation  that  their  incidence  can  be  most  satis- 
factorily explained  on  a  dietary  basis.    These  conditions  will  be 
further  considered  in  the  concluding  chapter. 

464.  More  About  the  Dietary  Habits  of  Early  Man. — Let 
us  return  to  our  consideration  of  the  dietary  habits  of  early  man. 
Since  he  was  not  able  to  cultivate  cereals  except  on  a  very  small 
scale  he  derived  most  of  his  sustenance  from  other  pursuits.    No 
one  will  question  the  statement  that  during  the  tribal  stage  in 
human  history,  hunting  and  fishing  were  the  principal  means  of 
obtaining  a  livelihood.    But  in  this  stage  of  his  development  very 
different  degrees  of  proficiency  existed  at  different  times,  depend- 
ing upon  the  weapons,  water  craft  and  fishing  devices  he  knew 
how  to  construct.    With  no  better  arms  than  a  stone  or  club  he 
could  not  successfully  hunt  the  larger  animals.    Lewis  and  Clark 
tell  of  a  tribe  of  Indians  that  they  visited  during  their  journey 
to  the  Pacific  coast  in  1804-7,  who  were  in  a  state  of  starvation 
while  surrounded  by  thousands  of  antelope  which  they  were  not 


420     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

able  to  kill  except  through  running  to  exhaustion  by  men  on 
horseback,  pursuing  them  in  relays.  This  condition  existed  even 
with  the  bow  and  spear  in  a  high  state  of  perfection. 

Hunting  in  temperate  or  torrid  regions  offered  but  a  very 
precarious  means  of  existence  for  man  except  in  a  few  favored 
regions  where  animals  such  as  the  bison  or  other  stupid  grazing 
animals  of  large  size  were  abundant.  The  seal  in  the  Arctic 
regions  formed  an  easy  prey.  It  was  largely  for  this  reason  that 
very  early  man,  whenever  possible,  dwelt  near  large  bodies  of 
water  where  fish  and  shell-fish  were  abundant,  for  they  were 
easier  to  secure,  and  offered  much  greater  certainty  of  a  food 
supply  than  did  hunting  for  large  quadrupeds.  A  carnivorous 
diet  derived  from  fish,  oysters,  clams,  and  other  living  creatures 
which  the  sea  or  the  large  rivers  afforded,  encouraged  primitive 
man,  whenever  possible,  to  become  a  shore  dweller.  The  numer- 
ous enormous  shell  heaps  or  kitchen  middens,  which  are  found 
along  the  Atlantic  coast  of  the  Americas  and  Europe  are  an 
illustration  of  this  mode  of  life  on  an  extensive  scale  on  the 
margins  of  these  continents.  These  sites  of  human  habitations 
were  built  up  through  many  generations  of  people  casting  aside 
the  shells  of  mollusks  which  served  them  as  food.  Here  we 
have  an  illustration  of  a  carnivorous  type  of  diet  in  which  all 
parts  of  the  animal  were  eaten.  This  practice  was  highly  satis- 
factory from  the  nutritive  standpoint,  and  very  superior  to  the 
present  one  of  eating  muscle  meats  to  the  exclusion  of  other 
tissues  which  would  make  good  its  deficiencies. 

465.  Domestic  Animals  Made  Possible  the  Utilization  of 
Grass  for  Conversion  into  Human  Food. — It  was  a  great  step 
in  advance  when  animals  from  which  the  horse,  cow,  goat,  sheep 
and  camel  have  descended,  were  domesticated.  With  these,  man 
was  able  to  invade  grassy  plains.  Their  animals  converted  coarse 
herbage  into  milk,  a  human  food  of  very  excellent  quality  and 
which  was  never  failing  in  its  supply.  Solicitude  for  his  animals, 
and  the  problems  of  protecting  and  caring  for  them,  stimulated 
mental  activity  and  cultivated  in  him  some  of  the  highest  attri- 
butes of  human  nature.  But  his  superior  nutrition  assured  him 
health  and  vigor,  and  made  him  capable  of  successfully  contend- 
ing with  his  neighbors  of  fertile  valleys  who  attempted  to  prac- 
tice agriculture,  or  who  subsisted  by  hunting,  and  he  dispossessed 
them,  at  will,  of  their  land  and  property.  He  migrated  from  his 
home  in  the  pasture  lands  only  at  intervals  when  drought  threat- 
ened to  destroy  his  flocks  and  herds,  but  when  he  left  his  home 


THE  DIETARY  HABITS  OF  MAN  421 

it  was  always  as  a  conqueror.  The  Jews,  moving  into  Palestine; 
the  Aryan  hoards  who  migrated  westward  and  peopled  Europe, 
and  the  Mongols,  who  under  Ghengis  Khan  and  his  successors 
dispossessed  their  neighboring  tribes,  were  all  pastoral  peoples. 
Their  descendants  of  to-day  live  as  did  their  ancestors  of  thou- 
sands of  years  ago,  the  lives  of  pastoral  nomads  on  the  pasture 
lands  of  Asia,  and  are  nourished  for  the  most  part  on  sour  milk. 
The  Cossacks  who  have  for  so  long  formed  the  backbone  of  the 
Russian  army  are  from  this  class,  and  the  ancestors  of  the  Turks 
were,  and  indeed  most  of  the  rural  Turkish  population  of  to-day 
are  pastoral  in  their  habits,  and  are  living  examples  of  the  fine 
physical  development  and  freedom  from  defects,  which  are  the 
inheritance  of  sour  milk  drinkers  generally.  The  sourness  of  the 
milk  which  they  use  as  food  is,  it  should  be  stated,  a  matter  of 
secondary  importance.  Prompt  souring  is  the  most  effective 
means  at  their  disposal  for  preserving  milk  in  a  wholesome 
condition. 

466.  Changes  in  the  Diet  During  the  Great  Industrial  Era. 
— The  development  of  the  modern  industrial  era  in  Europe, 
America,  and  the  other  parts  of  the  world  which  have  been 
colonized  by  Europeans,  has  seen  gradual  and  progressive 
changes  in  the  character  of  the  human  diet,  which  represent  an 
experiment  which  was  blindly  entered  into,  and  which  is  now 
proving  a  grievous  failure,  as  attested  by  the  pronounced 
tendency  to  physical  deterioration.  More  and  more,  cereals, 
meats  of  the  muscle  type,  and  tubers  have  become  the  prominent 
articles  which  nourish  the  Western  nations.  With  the  great 
increase  in  population  the  production  of  dairy  products  has  be- 
come more  and  more  a  precarious  business,  because  of  the  keen 
competition  of  vegetable  foods  in  the  market.  On  the  vast  ranges 
of  America,  Australia,  Argentina  and  elsewhere,  in  which  there 
is  but  scanty  rainfall,  beef  production  has  been  economically 
successful  and  has  tended  greatly  to  discourage  live  stock  pro- 
duction in  regions  better  suited  to  the  growing  of  farm  crops. 
The  dairy  industry  would  scarcely  have  continued  to  exist  until 
now  had  it  not  been  for  the  discovery  that  the  great  bulk  of  the 
agricultural  land  of  America  is  limited  in  its  fertility  by  its  low 
content  of  potassium,  phosphorus,  and  in  some  places  of  lime, 
and  soon  becomes  exhausted  when  cereal  or  other  crops  are  grown 
continuously  and  are  sold  off  the  farms.  Worn  out  farms  exist 
in  large  numbers  to-day  in  New  England  and  New  York  and 
elsewhere  in  the  East,  and  signs  of  soil  depletion  are  evident  in 


422     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

parts  of  the  great  wheat-growing  belt  in  the  northwest.  We  have 
no  adequate  sources  of  potassium  and  phosphorus  with  which  to 
replace  these  indispensable  plant  nutrients.  This  was  recognized 
years  ago  by  scientific  agriculturists,  and  the  agricultural  col- 
leges and  the  U.  S.  Department  of  Agriculture  have  urged  upon 
farmers  the  necessity  of  maintaining  a  flourishing  animal  in- 
dustry as  the  only  means  of  maintaining  a  permanent  system  of 
agriculture.  By  this  means  the  crops  are  fed  on  the  farm  and 
the  fertility  is  in  great  measure  preserved. 

467.  lodin  as  a  Limiting  Factor  in  Human  and  Animal 
Nutrition  in  Certain  Regions. — It  appears  to  have  become  es- 
tablished by  recent  observations  that  there  is  danger  in  certain 
parts  of  the  United  States  and  elsewhere,  of  human  beings  and 
animals  failing  to  secure  in  their  food  a  sufficient  amount  of 
iodin.  This  element  is  present  in  the  thyroid  gland  to  the  extent 
of  about  0.2  per  cent  of  the  dried  weight  of  the  gland,  or  about 
10  to  15  mgms.  in  the  entire  gland.  This  element  is  essential  for 
the  formation  of  an  organic  iodin-containing  compound  which 
acts  as  a  hormone  or  regulator  of  metabolism.  Kendall  (11)  has 
isolated  this  substance  from  the  thyroid  glands  of  animals  and 
has  given  it  the  name  thyroxin.  A  lack  of  iodin  in  the  diet  pre- 
vents the  formation  of  this  hormone  and  leads  to  hyperplasia  and 
enlargement  of  the  gland. 

Goiter  is  very  common  around  the  Great  Lakes,  in  the  upper 
Missouri  and  Yellowstone  valleys,  in  Eastern  Oregon  and  Wash- 
ington, and  has  been  attributed  to  lack  of  iodin  in  the  soil  and 
water  of  those  regions. 

Salmon  and  trout,  which  are  reared  under  hatchery  conditions 
and  fed  liver  and  are  crowded,  and  kept  in  water  which  is  not 
changed  frequently  enough,  have  suffered  greatly  from  goiter. 
It  has  been  shown  by  Marine,  Lenhart  and  others  (12)  that 
treatment  of  the  water  in  which  the  fish  are  kept,  with  potassium 
iodid,  causes  retrogression  of  the  thyroid  and  a  return  to  nor- 
mal. Feeding  the  fish  upon  hashed  sea-fish  also  led  to  im- 
provement in  the  condition  of  their  thyroids,  presumably  because 
sea-fish  contain  iodin.  Wild  fish  do  not  suffer  from  this  disease. 
Pike  and  bass  in  Lake  Erie  frequently  suffer  from  goiter  (13). 

In  the  Yellowstone  river  valley  there  has  been  for  some  time 
a  loss  of  approximately  one  million  young  pigs  and  numerous 
lambs,  calves  and  colts  each  year  as  the  result  of  thyroid  disease. 
This  most  serious  problem  in  animal  production  has  been  studied 
by  Smith  (14),  who  found  that  it  was  only  necessary  to  ad- 


THE  DIETARY  HABITS  OF  MAN 


423 


minister  sodium  or  potassium  iodid  to  the  pregnant  sows  in  order 
to  prevent  the  condition.  As  the  result  of  the  shortage  of  iodin 
many  of  the  pigs  were  born  dead,  others  died  within  an  hour  or 
two  while  still  others  lived  twenty-four  to  thirty-six  hours. 
These  pigs  were  born  in  a  hairless  condition,  and  with  great 
enlargement  of  the  thyroid  gland. 

Hart  and  Steenbock  (15)  have  reported  results  with  pigs  which 
are  confirmatory  of  those  of  Smith. 

Marine  and  Kimball  (16)  studied  the  effects  of  administering 
sodium  iodid  to  girls  in  the  public  schools  of  Akron,  Ohio,  on  the 
incidence  and  course  of  goiters  among  them.  In  a  complete 
census  of  the  condition  of  the  thyroid  gland  in  the  girls  from  the 
fifth  to  the  twelfth  grades  of  the  school  population  in  this  goiter- 
ous  district,  it  was  found  that  1,688  or  43.59  per  cent  had  normal 
thyroids;  2,184  or  56.41  per  cent  had  enlarged  thyroids,  and  594 
or  13.4  per  cent  had  well-defined,  persistent  thyroglossal  stalks. 

They  administered  sodium  iodid  to  a  large  number  of  these 
girls,  and  six  months  later  a  reexamination  of  their  thyroids  was 
made.  The  following  table  shows  the  results  and  also  the  data 
secured  with  another  group  of  girls  who  did  not  take  the  prophy- 
lactic treatment. 


Pupils  Taking  Prophylactic 
Treatment. 

Pupils. 

Per  Cent. 

Pupils  Not  Taking 
Prophylactic  Treat- 
ment. 

Pupils. 

Per  Cent. 

Thyroids  remained  normal  .    ... 

283 
0 
287 
141 
2 
34 
17 

100.0 
0.0 
66.0 
33.5 
0.5 
66.7 
33.3 

637 
259 
759 
10 
103 
106 
5 

74.0 
26.0 
87.0 
12 
11.8 
95.5 
4.5 

Increased  from  normal  to  slight  goiter 
Small  goiters  (unaltered)  

Small  goiters   (disappeared)  

Small  goiters  (increased)   

Large  goiters   (unaltered)  

Large  goiters   (decreased)  

Total   

764 
4,415 

1,879 

Total  number  of  girls  examined  

These  results  indicate  clearly  the  value  of  the  administration 
of  suitable  doses  of  iodids  at  intervals,  as  a  means  of  preventing 
the  hyperplasia  of  the  thyroid  gland. 

468.  The  Struggle  in  Agriculture  Between  Meat  Produc- 
tion and  Dairying. — The  struggle  in  the  animal  industry  for  su- 
premacy is  between  meat  production  and  dairying.  Beef,  pork 


424     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

and  mutton  have  the  advantage  in  respect  to  palatability,  for  they 
are  among  our  most  appetizing  foods.  Milk  cannot  compete  with 
meat  in  this  respect.  On  the  other  hand  milk  is  unique  as  a  food, 
and  especially  as  a  supplementary  food  which  when  used  in  suffi- 
cient amounts  corrects  the  deficiencies  of  a  diet  otherwise  com- 
posed of  cereals,  tubers  and  meats,  and  is,  therefore,  vastly  su- 
perior to  meat,  for  the  specific  purpose  which  is  of  greatest  signifi- 
cance both  from  the  standpoint  of  the  nation's  nutrition  and  from 
the  standpoint  of  economic  agriculture.  Armsby  (17)  has  calcu- 
lated from  a  large  amount  of  experimental  data,  that  because  of 
its  capacity  for  phenomenal  growth  24  per  cent  of  the  energy  of 
food  employed  in  pork  production  may  be  returned  by  the  animal 
as  human  food.  The  dairy  cow  is  capable  of  returning  at  least 
18  per  cent  of  the  energy  of  the  feed  she  consumes,  into  milk, 
whereas  the  beef  animal  or  the  sheep  return  in  the  form  of  edible 
meat  but  3.5  per  cent  of  the  energy  of  the  feed  which  they  con- 
sume. Economically,  therefore,  milk  production  is  the  logical 
business  to  promote,  even  from  the  standpoint  of  energy  values 
in  food,  but  since  the  cow  utilizes  for  milk  production  a  very 
large  part  of  her  total  nutrients  in  the  form  of  forage  plants, 
either  as  pasturage  or  hay,  she  appears  in  a  most  favorable  light 
as  a  producer  of  human  food.  Forage  crops  can  be  produced  in 
much  larger  quantities  on  a  given  acreage  than  can  cereal  grains 
or  other  seed  crops,  so  that  the  dairy  industry  is  an  economical 
method  of  producing  human  food,  as  well  as  an  effective  means 
of  conserving  the  fertility  of  the  soil  and  assuring  permanency 
of  yield  in  agriculture.  Any  industry  whioh  comes  into  com- 
petition with  it  has  economic  and  nutritional  features  which 
condemn  it  in  the  eyes  of  far-seeing  people. 

BIBLIOGRAPHY 

1.  Crichton-Browne,  J.:    Parcimony  in  nutrition,  New  York,  1909. 

2.  Chittenden,  R.  H. :    The  nutrition  of  man,  New  York,  1907. 

Physiological  economy  in  nutrition,  New  York,  1904. 

3.  McKay,  D.:    The  protein  element  in  nutrition,  London,  1912. 
Douglas,  L.  M.:    The  bacillus  of  long  life,  New  York,  1911. 

4.  McCollum,  E.  V.,  and  Simmonds,  N.:    Unpublished  data. 

5.  Herter,  C.  A.,  and  Kendall,  A.  L:    The  influence  of  dietary  alterations 

on  the  types  of  intestinal  flora,  Jour.  Biol.  Chem.,  1909-10,  vii,  203. 

6.  Hooton,  E.  A.:    On  certain  Eskjmoid  characters  in  Icelandic  skulls, 

Amer.  Jour,  of  Physical  Anthropology,  1918,  1,  53. 

7.  Kanzaki,    Kirchi:    Is   the   Japanese    Menace    in   America    a   reality? 

Present  day  immigration  with  special  reference  to  the  Japanese, 
Annals  of  the  Amer.  Acad.  of  Polit.  and  Soc.  Sci.,  1921,  xciii,  88. 


THE  DIETARY  HABITS  OF  MAN  425 

8.  Huntington,  E.:    Civilization  and  climate,  New  Haven,  1915. 

World  power  and  evolution,  New  Haven,  1919. 

9.  Semple,  E.  C.:    Influences  of  geographic  environment,  New  York,  1911. 

10.  Terman,  L.  M.:    The  hygiene  of  the  school  child,  Boston,  1914. 

11.  Kendall,  E.  C.:    The  isolation  in  crystalline  form  of  the  compound 

containing  iodine  which  occurs  in  the  thyroid,  Jour.  Amer.  Med. 
Assoc.,  1915,  Ixiv,  2043. 

12.  Marine,  D.,  and  Lenhart,  C.  H. :    Observations  on  the  so-called  thyroid 

carcinoma  of  brook  trout  and  its  relation  to  ordinary  goiter,  Bulletin 
No.  7,  Dept.  of  Fisheries,  Commonwealth  of  Pennsylvania,  1910. 

13.  Marine,   and   Lenhart:    On   the   occurrence   of   goiter   in   fish,   Johns 

Hopkins  Hosp.  Bull.,  1910,  xxi,  95. 

14.  Smith,  G.  E.:    A  study  of  the  iodine  requirement  of  the  pregnant  sow, 

Jour.  Biol.  Chem.,  1917,  xxix,  215. 

15.  Hart,  E.  B.,  and  Steenbock,  H.:    Thyroid  hyperplasia  and  the  relation 

of   iodine   to   the   hairless   pig    malady,   Jour.   Biol.    Chem.,    1918, 
xxxiii,  313. 

16.  Marine,  D.,  and  Kimball,  O.  P.:    The  prevention  of  simple  goiter  in 

man,  Jour.  Lab.  and  Clin.  Med.,  1917,  iii,  3. 

Kimball,  and  Marine:    The  prevention  of  simple  goiter  in  man,  Arch, 
of  Int.  Med.,  1918,  xxii,  41. 

17.  Armsby,  H.  P.:    "Roast  Pig",  Science,  1917,  xlvi,  160. 


CHAPTER  XVIII 

THE  MOST  FUNDAMENTAL  PROBLEM  IN 
PREVENTIVE  DENTISTRY 

469.  Recognition  of  the  Need  of  Strengthening  the  Social 
Fabric. — Many  thinking  people   are  now   calling  attention  to 
the  imperative  need  of  strengthening  the  social  fabric.     Hunt- 
ington   (1)   points  out  that  this  can  be  accomplished  only  by 
improvement  in  the  inherited  factors,  in  the  health   and  the 
training  of  our  children.    He  emphasizes  that  good  inheritance 
or  good  training  can  serve  the  individual  only  when  health  per- 
mits.   It  will  be  accepted  by  all  that  heredity  and  training  form 
the  most  important  levers  of  accomplishment,  and  that  they  can 
act  effectively  only  from  the  fulcrum  of  health.     The  man  or 
woman  who  is  always  tired,  or  who  feels  no  joy  in  actively  prose- 
cuting the  work  in  which  he  or  she  is  engaged,  who  is  easily  dis- 
heartened  and   downcast   because   of  personal   prospects,   who 
struggles  on  more  from  a  sense  of  dread  of  becoming  a  dependent 
upon  others  than  from  confidence  that  victory  will  still  come  as 
a  reward,  is  essentially  the  victim  of  poor  health, 

470.  The  Importance  of  Physical  Well-Being. — The  value 
of  an  individual  to  society  will  be  determined  in  great  measure 
by  the  way  he  feels.    His  capacity  for  energy  output  and  activity, 
his  estimate  of  himself  and  his  attitude  toward  his  environment, 
are  profoundly  influenced  by  his  physical  condition.    That  emo- 
tion cannot  be  separated  from  its  physical  concomitants  has  been 
for  many  years  recognized  by  psychologists.     Dislike  of  one's 
work,  idling  away  of  one's  time,  lack  of  enthusiasm  for  one's 
undertaking,  and  lack  of  hope,  take  root  probably  from  some 
physical  basis.    Derangement  of  the  metabolic  functions  is  gen- 
erally the  underlying  cause  for  lack  of  appreciation  of  the  im- 
portance of  tact,  for  lack  of  respect  for  others  and  for  failure 
to  discern  the  futility  of  antagonizing  others.     No  elements  of 
human  conduct  contribute  more  to  bring  about  failure  than  do 
these. 

Much  unhappiness  results  from  ease  of  irritation  and  over- 

426 


THE  PROBLEM  IN  PREVENTIVE  DENTISTRY   427 

sensitiveness.  One's  attitude  toward  authority  and  conditions  in 
conflict  with  one's  desires  are  the  results  of  bodily  conditions. 
Except  in  relatively  rare  cases  where  mental  defect  is  inherited 
there  is  no  gloom  in  the  mind  of  the  physically  well.  There  are 
not  wanting  to-day  persons  with  wide  experience,  who  hold  the 
view  that  much  of  the  delinquency  among  children  and  criminal 
tendencies  among  adults  are  due  to  physical  defects.  There  is 
danger  that  we  attribute  too  much  to  heredity.  Treadway  (1), 
in  reporting  upon  his  studies  of  delinquents,  says:  "Bad  progeni- 
tors, pernicious  environment  and  poor  educational  opportunities 
form  an  insufficient  basis  upon  which  to  classify  personality." 

471.  Evidences  of  Physical  Deterioration. — Keen  observers 
have  expressed  during  the  last  century,  their  belief  that  in  a 
large  part  of  the  population  of  Europe  and  America,  physical 
deterioration  was  seriously  in  progress.  Herbert  Spencer,  writing 
seventy-five  years  ago  of  the  bodily  endurance  of  England's 
people,  stated  that,  "Thus  far  we  have  found  no  reason  to  fear 
trials  of  strength  with  other  races.  .  .  .  But  there  are  not  want- 
ing signs  that  our  powers  will  presently  be  taxed  to  the  utter- 
most." Twenty  years  ago  General  Sir  Frederick  Maurice,  in 
discussing  the  health  of  his  nation,  warned  England  that  there 
were  grave  signs  of  national  deterioration,  made  evident  by  the 
failure  of  nearly  three  out  of  every  four  young  men  to  come 
up  to  the  standard  required  for  ordinary  military  home  service 
even  in  time  of  peace  (2) . 

The  lack  of  physical  fitness  was  seen  to  lie  in  the  universal 
prevalence  of  under-developed  and  feeble  jaws,  and  inferior  and 
decayed  teeth,  poorly  developed  nose  and  throat,  adenoids,  weak 
chests  and  indigestion.  These  undermine  the  constitution,  dwarf 
the  body  and  predispose  to  disease.  The  widespread  prevalence 
of  rickets  in  childhood,  and  in  later  life  the  high  incidence  of 
tuberculosis  are  but  two  of  the  direct  manifestations  of  faulty 
development.  The  leading  causes  of  this  grave  tendency  to  de- 
terioration in  the  younger  generation  were  referred  to  unfitness 
for  motherhood,  lack  of  essential  knowledge  on  the  part  of 
parents,  bottle-feeding  in  early  infancy,  defective  hygiene  and 
too  much  pap-feeding  of  children.  From  what  has  been  said  in 
earlier  chapters  on  the  basis  of  animal  experimentation  and 
human  experience  in  different  parts  of  the  world,  it  will  be  evi- 
dent that  this  explanation  does  not  bring  out  with  clarity,  nor 
emphasize  sufficiently  the  fundamental  significance  of  the  choice 
of  food  in  mother  and  offspring. 


428     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

472.  The  Bottle-Feeding  of  Infants. — Bottle-feeding  results 
in  serious  injury  to  infants,  principally  because  of  ignorance  re- 
garding the  kind  of  food  necessary  for  their  normal  development. 
Modified  milks  in  which  wrong  proportions  exist  among  the 
several  food  elements;  bad  bacteriological  conditions  of  the  food 
or  of  the  bottle;  under- feeding  or  over-feeding,  together  with  the 
early  substitution  of  cereal  and  other  foods  unfit  for  the  nutri- 
tion of  infants,  are  the  actual  causes  of  subnormal  development, 
rather  than  artificial  feeding  in  itself.     These  are  the  causes 
which  are  undermining  the  vitality  of  the  rising  generation,  and 
have  already  markedly  reduced  the  stamina  of  the  present  gen- 
eration of  adults. 

473.  Some  New  and  Unfavorable  Influences  Are  at  Work 
to  Undermine  Health. — If  one  examines  the  writings  of  those 
of  to-day  who  are  most  active  in  studying  the  health  problems  of 
children  and  in  arousing  the  nation  to  activity  in  their  behalf, 
one  finds  various  causes  assigned  for  existing  conditions.     All 
would  agree  that  we  must  attribute  our  physical  deterioration 
to  subjection  of  the  human  race  to  new  and  unfavorable  condi- 
tions, but  differences  of  opinion  exist  as  to  the  nature  and  rela- 
tive importance  of  these.     The  seclentarjLJif e ;  the  life  within 
houses  instead  of  out  of  doors;  the  wearing  of  clothing  instead 
of  exposing  the  skin  to  the  weather  with  its  changing  conditions ; 
the  eating  of  soft  cooked  food  instead  of  raw  coarse  food;  the 
debilitating  effects  of  certain  climates;  the  preservation  of  weak- 
lings through  improved  hygiene  and  care;  the  artificial  feeding 
of  infants  instead  of  nursing;  the  burden  of  responsibilities  of 
civilized  life,  both  mental  and  moral,  and  the  failure  to  care 
for  the  hygiene  of  the  mouth  are  among  the  causes  most  promi- 
nent.   Doubtless  each  of  these  plays  its  part  in  contributing  to 
place  civilized  man  in  many  parts  of  the  world  in  his  present 
unenviable  position  with  respect  to  health.    It  can  now,  however, 
be  asserted  with  assurance,  that  the  chief  factor  responsible  for 
human  deterioration  in  recent  times  is  not  included  in  the  above 
list.    The  chief  factor  lies  in  the  unwise  choice  of  food. 

474.  Some  Observations  on  American  School  Children. — It 
would  be  out  of  place  here  to  recite  at  length  statistics  which 
reveal  the  seriousness  of  our  own  problem  of  malnutrition,  but 
a  few  facts  brought  to  light  by  the  examination  of  a  large  part 
of  the  twenty  million  school  children  in  the  United  States  should 
be  mentioned.     Miss  Leete,   of  the  American   Child   Hygiene 
Association  (3),  summarizes  these  statistics  by  stating  that  ac- 


THE  PROBLEM  IK  PREVENTIVE  DENTISTRY    429 

cording  to  them  1  per  cent  of  the  children  are  mentally  defective ; 
that  5  per  cent  are  tuberculous  now  or  have  been  in  the  past; 
that  5  per  cent  have  defective  hearing;  that  25  per  cent  have 
defective  sight;  that  15  to  25  per  cent  have  diseased  tonsils  or 
adenoids;  that  10  to  20  per  cent  have  deformed  feet;  that  50  to 
75  per  cent  have  defective  teeth  and  that  15  to  25  per  cent  suffer 
from  malnutrition.  The  discovery  of  the  nature  of  the  defects 
brings  forth  an  incentive  to  inquire  into  the  causes  producing 
them,  and  an  understanding  of  the  etiology  of  these  conditions 
gives  courage  to  undertake  the  task  of  rendering  assistance. 

475.  More    Can   Be   Achieved  Through    Dietary    Reform 
Than  Through  Any  Other  Agency. — In  preceding  chapters  data 
are  presented  which  show  the  basis  of  the  establishment  of  diet- 
ary habits  which  in  great  measure  would  bring  about  within  two 
generations  a  return  to  physical  standards  in  man  closely  approxi- 
mating the  best  which  have  been  realized  in  human  history. 
There  is  nothing  more  important  than  the  institution  of  dietary 
reforms  in  accordance  with  the  scientific  knowledge  set  forth  in 
these  pages.    The  validity  of  the  conclusions  drawn  from  human 
experience  and  animal  experimentation  has  already  been  veri- 
fied in  several  places  by  the  scientific  feeding  of  school  children. 
Notable  among  these  are  the  triumphs  of  Mrs.  Ira  Couch  Wood 
of  Chicago  (4),  and  of  Miss  Maude  A.  Brown  of  Kansas  City, 
Mo.  (5) .    These  results  have  been  obtained  essentially  by  liberal 
feeding  of  milk  to  undernourished  school  children.    They  repre- 
sent the  degree  to  which  children  who  have  been  badly  started 
in  life  and  who  are  suffering  from  retardation  of  growth  and  other 
physical  handicaps  respond  merely  to  proper  feeding  and  rest. 
This  tends  to  overcome  the  injurious  effects  of  diseased  tonsils, 
poor  and  infected  teeth  and  other  ailments  which  many  have 
believed  the  clinic  could  successfully  cope  with  only  by  means 
of  surgery. 

476.  The  Story  of  Adam. — Most  striking  among  the  results 
obtained  by  Mrs.  Wood,  of  the  Elizabeth  McCormick  Memorial 
Fund,  is  the  history   of  Adam.    This  boy  was  in  very  poor 
physical  condition,  at  the  age  of  fourteen  years,  when  the  eco- 
nomic condition  of  his  family  required  that  he  seek  employment. 
He  was  refused  a  permit  to  work  as  a  minor  because  of  his  frail 
condition.    Mrs.  Wood  produced  a  complete  transformation  in 
him  during  twelve  weeks,  by  feeding  him  liberally  with  milk,  of 
which  he  drank  large  quantities.    From  23  per  cent  under  weight, 
he  reached  the  normal  for  his  height  during  this  period,  and  on 


430     THE  NEWER  KNOWLEDGE  OF  NUTRITION 

again  applying  for  a  permit  to  work  had  no  difficulty  in  passing. 
He  was  transformed  from  a  feeble  child  to  a  strong  and  vigorous 
boy  in  three  months  by  changing  his  diet  and  taking  rest.  Em- 
phasis upon  rest  is  of  very  great  importance  to  children  who  are 
in  a  poorly  nourished  condition.  It  is  impossible  to  appreciate 
the  transformation  of  this  boy,  except  through  a  comparison  of 
his  photographs  before  and  after  the  dietetic  treatment.  There 
are  many  thousands  of  boys  and  girls  in  the  country  to-day  who 
could  be  similarly  transformed. 

477.  Prenatal  Life,  Infancy  and  Early  Childhood  Are  the 
Critical  Periods. — The  greatest  good  is  to  come  to  the  next  gen- 
eration, so  far  as  educational  effort  can  accomplish  its  purpose, 
through  the  solicitude  of  mothers  and  fathers  in  so  caring  for 
their  unborn  and  born  children  as  to  obviate  the  establishment 
of  those  physical  defects  which  not  only  prevent  normal  muscu- 
lar development  but  which  affect  the  entire  outlook  upon  life. 
"Flat  feet,"  or  broken  arches,  feeble  musculature  and  low  muscle 
tone,    which    induce    faulty    posture,    are    factors    determining 
whether  the  child  will  experience  pleasure  in  activity  and  com- 
petition with  his  associates.     One  victory  in  a  game  causes  a 
desire  for  other  victories,  and  confidence  in  self  and  the  belief 
that  effort  will  be  rewarded  by  achievement  are  the  direct  result 
of  successful  participation  in  closely  contested  games.    Although 
there  are  many  examples  of  great  achievement  by  persons  whose 
physical  constitutions  were  below  the  average  or  even  decidedly 
inferior,  it  is  nevertheless  true  that  physical  handicaps  usually 
determine  the  angle  from  which  life  is  viewed.     Children  who 
are  below  the  optimum  in  physical  well-being  do  not  radiate 
happiness,  but  tend  to  view  the  outlook  with  discontent  and  to 
brood  over  the  hardness  of  life  rather  than  eagerly  to  seek  its 
opportunities  with  the  expectation  of  bettering  their  own  and 
the  condition  of  others.    Physical  perfection  is  the  greatest  assur- 
ance that  the  individual  will  make  an  effort,  and  lack  of  effort 
or  failure  to  do  one's  best  is  to  the  average  human  being  the 
worst  handicap  to  success. 

478.  Malnutrition  Is  Usually  the  Primary  Cause  of  Physical 
Inferiority  in  Childhood. — Malnutrition  is  not,  as  many  have 
hitherto  believed,  ordinarily  the  secondary  result  of  those  physi- 
cal defects  which  the  clinic  seeks  to  remedy,  but  it  is  the  primary 
cause  from  which  these  physical  defects  generally  arise.     Fur- 
thermore, the  present  widespread  view  that  the  most  important 
task  in  hand  is  the  medical  treatment  of  those  children  in  whom 


THE  PROBLEM  IN  PREVENTIVE  DENTISTRY    431 

clinically  discernible  defects  exist  is  a  mistaken  one.  First  in 
importance  both  from  the  standpoint  of  the  physically  defective 
child  and  of  the  national  welfare,  is  the  establishment  of  nu- 
tritive conditions  which  are  regulated  as  nearly  as  possible  with 
the  scientific  precision  necessary  to  insure  optimal  well-being. 
The  clinic  should  occupy  second  place  in  the  scheme  of  human 
betterment. 

479.  The  Basis  of  Preventive  Dentistry  Is  Satisfactory 
Nutrition  During  Development. — A  similar  error  is  widespread 
concerning  the  most  effective  method  of  solving  the  problem  of 
protecting  the  teeth  from  decay.  In  a  recent  publication  Clark 
and  Butler  (6)  state  "Dental  caries  is  caused  by  the  action  of 
bacteria  or  germs,  which  normally  inhabit  the  mouth.  These 
germs,  acting  in  the  presence  of  food  debris  and  certain  elements 
in  the  saliva,  result  in  the  formation  of  an  acid  which  attacks  the 
enamel  covering  the  exposed  parts  of  the  tooth,  after  which  the 
underlying  softer  parts  become  rapidly  destroyed.  Many  other 
factors  are  actual  and  potential  causes  of  dental  decay  and  its 
progress,  such  as — 1.  Low  resistance  of  the  teeth  to  decay  be- 
cause of  developmental  defect  (antenatal  and  postnatal).  2. 
Faulty  diet  (both  of  the  mother  during  pregnancy  and  of  the 
child).  3.  Neglect  of  dental  attention  through  ignorance  of  the 
parents.  4.  The  cost  of  dental  attention,  a  serious  consideration 
with  families  of  low  economic  status.  5.  Failure  of  the  child  to 
call  attention  to  the  condition  of  the  teeth,  either  because  it  is 
too  young  or  because  of  fear.  6.  Lack  of  dental  facilities,  so 
common  in  rural  sections."  It  is  pointed  out  by  these  authors 
that  a  very  high  percentage  of  undernourished  children  show 
marked  evidence  of  dental  decay.  They  cite  the  results  of  the 
examination  of  270  children  by  the  Public  Health  Service,  which 
showed  that  33  per  cent  of  these  had  from  1  to  4  cavities,  48  per 
cent  had  from  4  to  8,  and  some  had  9,  10  and  11  cavities.  It  is 
to  be  regretted  that  this  excellent  paper  fails  to  emphasize  the 
importance  of  including  in  the  campaign  for  the  preservation  of 
the  teeth,  an  effort  to  change  the  character  of  the  nation's  diet, 
in  order  that  developmental  defects  shall  grow  less  common  and 
less  severe  as  time  passes.  Emphasis  is  laid  entirely  upon  the 
importance  of  the  dental  hygienists,  who  limit  their  work  to 
cleaning  and  polishing  all  surfaces  of  the  teeth  above  the  gum 
margins,  to  the  dental  clinic  for  the  repair  of  the  teeth  already 
in  a  state  of  decay  and  to  the  teaching  of  mouth  hygiene.  Such 
a  program  is  based  upon  the  belief  that  cleanliness  of  the  oral 


432      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

cavity  is  of  first  importance  as  a  preventive  measure  for  preserv- 
ing the  teeth.  Terman  (7)  says:  "We  know  that  a  clean  tooth,  a 
tooth  that  is  kept  clean,  cannot  decay."  Butler  (8) ,  in  a  recent 
article  states  "  ...  it  is  but  a  matter  of  a  few  generations  before 
civilized  man  will  be  edentulous  or  without  teeth.  The  possi- 
bility of  persuading  the  people  of  to-day  to  subsist  upon  a  coarser 
diet  is  most  remote  and  it  will  be  at  once  seen  that  our  only  hope 
in  this  direction  lies  in  some  prophylactic  measure."  He  further 
states:  "Just  as  in  preventive  medicine  lies  the  greatest  good  in 
all  medical  science,  so,  too,  in  dental  prophylaxis  is  to  be  found 
the  nearest  solution  of  this  problem.  The  establishment  of  a 
dental  clinic  in  a  school  and  the  employment  of  competent  per- 
sons to  care  for  the  mouths  of  the  younger  children  comes 
nearest  to  the  requirements."  And  he  further  says:  "Every 
hygienic  measure  adopted  strengthens  the  position  of  others  that 
may  be  in  practice,  but  in  the  whole  field  of  hygiene  there  is  no 
single  part  that  can  approach  the  hygiene  of  the  mouth  in 
importance." 

480.  The  Prevailing  Ideas  Regarding  Preventive  Dentistry 
Are  Based  on  Wrong  Premises. — These  quotations  represent 
fairly  the  position  now  being  taken  by  almost  if  not  quite  all 
of  the  physicians  and  dentists  who  have,  through  their  energy 
and  solicitude  caused  the  development  of  the  present  movement 
for  preservation  of  the  teeth  of  the  rising  generation  through 
repair  and  mouth  hygiene.  All  efforts  in  this  direction  deserve 
the  highest  commendation,  but  anyone  who  gives  much  thought 
to  this  subject,  and  who  is  familiar  with  modern  research  in  the 
field  of  nutrition,  must  come  to  the  conclusion  that,  valuable  as 
is  this  movement  for  the  welfare  of  the  children  of  the  present 
day,  it  falls  lamentably  short  of  being  a  comprehensive  program 
from  the  standpoint  of  the  race  and  the  nation.  But  these  quota- 
tions from  leading  authorities  give  a  true  picture  of  the  present 
day  situation  in  preventive  dentistry.  In  England  and  America 
we  are  in  the  stage  of  progress  where  repair  and  cleanliness  are 
goals  toward  which  school  authorities  and  parents  are  being 
urged  to  work.  This  is  essentially  an  attractive  superstructure 
without  a  firm  foundation.  In  its  present  form  this  movement 
for  the  preservation  of  the  nation's  teeth  is  founded  upon  a  plan 
which  will  call  for  more  and  ever  more  investment  of  time,  money 
and  human  effort  with  no  prospect  of  relief  from  the  burden. 
This  is  became  it  ignores  the  developmental  factor.  The  only 
logical  and  far-seeing  policy  is  to  inquire  into  the  "cause  of  the 


THE  PROBLEM  IN  PREVENTIVE  DENTISTRY  433 

poor  quality  and  vulnerability  of  the  present  generation,  and  to 
take  up  the  task  of  instituting  reforms  in  our  habits  of  living 
which  will  free  the  next  generation  from  the  defects  from  which 
we  are  now  suffering. 

Present  activities  in  relation  to  dental  prophylaxis  may  well 
be  likened  to  the  institution  of  a  rigid  quarantine  in  an  epidemic 
of  typhoid  fever  brought  about  by  an  infected  milk  supply,  but 
without  making  any  effort  to  check  the  delivery  of  the  dangerous 
milk.  We  should  not  be  getting  at  the  root  of  the  evil.  In  the 
prevention  of  dental  caries,  the  only  effective  measure  is  to  adopt 
a  policy  which  will  result  in  the  formation  of  a  dental  mechan- 
ism possessing  its  own  barriers  of  defence.  This  involves  the 
developmental  factor,  which  those  now  out  of  infancy  no  longer 
have  the  opportunity  to  profit  by,  but  we  can  easily,  if  we  apply 
the  scientific  principles  of  nutrition  to  the  daily  life  of  the  nation, 
leave  to  our  children's  children  the  priceless  heritage  of  freedom 
from  the  physical  suffering  which  we  ourselves  must  bear,  not 
only  from  mouth  discomfort,  but  from  rheumatism,  heart  disease 
and  other  ailments  having  their  origin  in  infected  teeth.  When 
dietary  reforms  are  instituted  sufficiently  effective  to  bring  about 
this  result,  and  when  in  addition  the  dental  clinic  is  established 
in  the  public  schools  on  a  scale  adequate  to  meet  the  present 
day  need  for  repair,  we  shall  have  a  comprehensive  dental  pro- 
gram which  will  in  due  time  accomplish  the  great  objective — the 
eradication  of  dental  caries.  This  is,  however,  but  one  of  a  num- 
ber of  most  fundamental  achievements  to  be  realized  by  effec- 
tively carrying  out  such  a  program. 

481.  The  Most  Satisfactory  Type  of  Diet. — In  concluding 
this  chapter  it  may  be  well  to  epitomize  the  system  of  living  by 
means  of  which  we  and  our  descendants  may  recover  the  physical 
prestige  we  are  rapidly  losing  owing  to  changed  conditions  of 
living,  especially  with  respect  to  our  food  habits.  The  system  of 
diet  which  can  be  confidently  recommended  with  assurances  that 
it  will  go  a  long  way  toward  improving  the  physical  fitness  of 
the  nation  is  a  very  simple  one,  and  its  daily  practice  involves 
no  great  self-denial.  It  involves  the  borrowing  of  the  best  ele- 
ments in  those  several  systems  of  diet  which  have  been  thor- 
oughly tested  in  human  experience  and  have  been  found 
successful. 

The  first  and  most  important  principle  is  the  extension  of  the 
use  of  dairy  products.  Instead  of  the  present  consumption  of 
half  a  pint  of  milk  a  day  there  should  be  at  least  a  quart  per 


434      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

capita.  Somewhat  more  than  this  would  probably  be  nearer  the 
optimum.  This  is  the  feature  of  the  diet  of  all  the  pastoral  peo- 
ples of  the  past  and  present,  which  made  them  superior  in  physi- 
cal perfection  to  all  other  peoples.  The  second  principle  to  be 
kept  in  mind  is  that  there  are  dietary  properties  TIT  the  leafy 
vegetables,  which  are  unique  among  foods  of  vegetable  origin. 
These  have  been  the  "protective  foods"  for  many  of  the  Asiatic 
peoples.  Their  consumption  in  liberal  quantities  as  regular  con- 
stituents of  the  diet  serves  not  only  to  provide  the  body  with 
valuable  nutrients  it  cannot  secure  in  adequate  amounts "Trom 
milled  cereals,  tubers  and  muscle  meats,  but  also  serves  to  main- 
tain the  intestinal  tract  in  a  hygienic  condition  through  promot- 
ing prompt  elimination.  Milk  likewise  serves,  through  its  en- 
couragement of  the  growth  of  lactic  acid-producing  organisms 
(which  cause  souring  of  milk) ,  to  bring  about  the  disappearance 
from  the  intestine  of  those  types  of  bacteria  causing  putrefactive 
decomposition  of  the  food  residues  with  the  production  of  sub- 
stances which  are  a  physiological  abomination.  This  principle, 
first  enunciated  by  Metchnikoff,  is  shown  by  modern  bacterio- 
logical studies,  to  be  sound.  Milk  has,  however,  dietary  prop- 
erties which  the  famous  bacteriologist  did  not  discern,  and  which 
make  it  the  one  food  for  which  there  is  no  effective  substitute. 

It  is  essential  to  keep  also  in  mind  the  third  principle  of  great 
importance  in  nutrition,  viz.,  that  of  takinfregularly  a  certain 
amount  of  raw  vegetable  food  for  the  specific  purpose  of  provid- 
ing the  body  with  a  sufficient  amount  of  the  anti-scorbutic 
substance. 

If  these  simple  principles  are  adhered  to,  the  main  features  of 
an  adequate  diet  will  be  fulfilled,  and  the  remainder  of  the  food 
supply  may  safely  be  derived  from  any  of  our  ordinary  milled 
cereal  products,  tubers,  root  vegetables,  meats,  etc.  It  is  dis- 
tinctly to  be  recommended  on  physiological  grounds,  however, 
that  the  consumption  of  meats  be  kept  at  a  somewhat  lower  plane 
than  is  now  the  rule. 

It  would  be  beyond  the  scope  of  the  present  discussion  of 
nutrition  to  discuss  in  an  adequate  way  the  details  of  putting 
into  effect  in  the  home  the  ideal  system  of  diet.  Miss  Simmonds 
and  the  author  have  treated  this  subject  adequately  elsewhere 
from  the  point  of  view  of  the  housewife  (9) .  It  must  suffice  here 
to  say  that  aside  from  the  liberal  use  of  milk  in  the  many  ways 
in  which  it  can  enter  into  the  diet  without  in  any  way  disturbing 
our  established  food  habits,  the  desired  end  is  to  be  attained 


THE  PROBLEM  IN  PREVENTIVE  DENTISTRY    435 

through  the  daily  consumption  of  the  vegetables  we  class  as 
greens  or  pot-herbs,  and  through  the  practice  of  eating  salad 
dishes  twice  a  day. 

482.  Mistaken  View  Regarding  the  Cause  of  the  Physical 
Excellence  of  Primitive  Peoples. — It  is  not  essential  that  we 
retrogress  to  a  state  of  social,  educational  or  ethical  inferiority 
in  order  to  enjoy  the  physical  fitness  frequently  seen  in  half 
savage  peoples.    Too  much  emphasis  has  been  placed  upon  the 
beneficial  effects  from  the  standpoint  of  health,  of  hardship  and 
exposure  to  which  primitive  man  was  of  necessity  subjected. 
Hardship  and  exposure  never  did  anyone  good.    Protection  from 
the  elements  is  conducive  to  health,  as  is  also  freedom  from  ex- 
cessive  exertion.    The   factors   which   have   tended   to   reduce 
civilized  man  to  a  state  of  physical  inferiority  as  compared  with 
his  barbarous  forebears  are  in  great  measure  due  to  changes  in 
the  character  of  his  diet.    We  can  easily  regulate  our  daily  fare 
to  be  essentially  optimal  from  the  standpoint  of  meeting  the 
chemical  needs  of  the  body,  and  at  the  same  time  to  make  it  of 
a  nature  which  will  necessitate  chewing  for  the  express  benefit 
of  the  development  of  the  jaws  and  teeth. 

483.  Concluding  Statement. — In  the  course  of  these  pages, 
I  have  traced  the  beginnings  of  the  development  of  exact  knowl- 
edge of  the  processes  of  nutrition,  and  have  shown  how  the 
science  expanded  through  the  intricate  reasoning  and  refined  ex- 
perimental studies  of  an  era,  the  great  popularity  of  which  has 
not  yet  begun  to  wane.    The  fundamental  principles  have  been 
illustrated  in  all  cases  through  the  results  of  animal  experimenta- 
tion.   After  these  fundamentals  had  been  established  there  fol- 
lowed a  study  of  human  experience  with  diet,  throughout  history 
man's^most  pressing  problem,  and  finally  an  application  of  the 
discoveries  of  this  branch  of  physiological  science  to  an  interpre- 
tation of  certain  of  the  present  day  problems  of  health  and  their 
solution.    It  has  been  a  joy  to  do  this.    The  concentrated  efforts 
of  the  author  during  a  period  of  fourteen  years  have  been  devoted 
to  observing  the  effects  of  diets  of  different  types  on  experi- 
mental animals.    During  this  time  a  continuous  search  has  been 
carried  on  for  information  of  any  and  every  kind  which  would 
aid  in  correlating  the  results  of  the  laboratory  with  those  of  prac- 
tical experience.    Year  by  year  this  has  increased  his  conviction 
that  the  scientific  discoveries  in  the  field  of  nutrition  are  des- 
tined to  be  recognized  as  the  most  fundamental  of  the  agencies 
that  contribute  to  the  health,  happiness  and  achievement  of  man. 


436      THE  NEWER  KNOWLEDGE  OF  NUTRITION 

Some  time  must  elapse  before  a  full  appreciation  of  the  impor- 
tance of  approximating  the  optimum  in  the  character  of  the  food 
supply  can  be  expected,  but  when  appreciated  at  its  full  value, 
our  knowledge  in  the  field  of  the  science  of  nutrition  will  be  re- 
garded as  our  most  precious  possession. 

BIBLIOGRAPHY 

1.  Huntington,  E.:     World  power  and  evolution,  New  Haven,  1919,  p.  18. 
Treadway,    W.   L.:      Psychiatric    studies    of    delinquents,      iv.    Public 

Health  Reports,  Wash.,  D.  C.,  1920,  xxxv,  1575. 

2.  Spencer,  H.:     Cited  by  Truby  King,  in  The  story  of  the  teeth.    Bul- 

letin issued  by  the  Babies  of  the  Empire  Society,  Melbourne  and 
London. 
Maurice,  F.:     Ibid. 

3.  Leete,  H.  L.:     The  school's  responsibility,  Mother  and  Child,  1921,  ii, 

358.    Amer.  Child  Hygiene  Assn.,  Baltimore. 

4.  Wood,  Mrs.  Ira  Couch:     Elizabeth  McCormick  Memorial  Fund  Publi- 

cation, Chicago. 

5.  Brown,  M.  A.:    A  study  of  malnutrition  of  school  children,  Jour.  Amer. 

Med.  Assoc.,  1920,  Ixxv,  27. 

6.  Clark,  T.,  and  Butler,  H.  B.:     Children's  teeth,  a  community  responsi- 

bility, Pub.  Health  Reports,  Wash.,  D.  C.,  1920,  xxxv,  2763,  Nov.  19. 

7.  Terman,  L.:     Dental  clinics.     In  Standards  of  Child  Welfare.     Con- 

ference Series   No.   1.     Children's  Bureau,  U.   S.   Dept.   of  Labor, 
Wash.,  D.  C.,  1919,  p.  234. 

8.  Butler,  H.  B.:     Importance  of  oral  hygiene  during  childhood,  Amer. 

Jour,  of  Pub.  Health,  1921,  xi,  297. 

Butler,  H.  B.:     The   fate   of  the  first   molar,  Pub.  Health  Reports, 
Wash.,  D.  C.,  1921,  xxxvi,  429. 

9.  McCollum,  E.  V.,  and  Simmonds,  Nina:     The  American  Home  Diet; 

An  answer  to  the  ever-present  question:     What  shall  we  have  for 
dinner?    Detroit,  1920. 


FIG.  20. — Illustrates  the  extent  to  which  the  teeth  have  degenerated  among  Americans 
in  recent  times.  The  trouble  lies  in  great  measure  in  faulty  nutrition  during  prenatal 
life,  infancy  and  childhood.  A  satisfactory  diet  is  essential  for  the  development  of  a 
sound  set  of  teeth.  If  the  jaws  and  teeth  are  poorly  developed  they  must  throughout 
life  be  vulnerable  to  bacterial  agencies. — Courtesy  of  The  Forsyth  Dental  Clinic. 


INDEX 


Accessory  food  factors,  248,  363 
Acroyd  and  Hopkins,  63 
Activator  of  Schaumann,  207 
Adam,  story  of,  429 
Adenin,  anti-neuritic  properties  of, 

223 

Agriculture,   early,  416,  418 
relation    of    type    of,    to   rickets, 

318,  323 

Alcohol  in  fermented  milks,  407 
Almond  oil,  23 
Aluminum,  16,  24 
Amino  acids,  29,  30 

basis  of  biological  value  of  pro- 
teins, 85 
certain,  indispensable  in  nutrition, 

91 

content  of,  in  seeds,  84 
from  proteins,  4 
in  "protein-free  milk,"  67,  76 
synthesis  of,  in  body,  65 
transmutability  of,  into  others,  63 
yields  of,  by  proteins,  92-98 
Ammonia,  can  it  replace  protein  in 

nutrition,  65 

from  protein  hydrolysis,  92,  94 
Analysis  of  foods,  3 
Animal    experimentation    and    pre- 
ventive medicine,  358 
experiments    and    human    experi- 
ence in  nutrition,  435 
fats,  vitamin  content  of,  145 
industry   and  permanent   agricul- 
ture, 421 

tissues,  correlation  of  function 
with  nutritive  properties,  143- 
147 

tissues,  dietary  properties  of,  143 
Anti-rachitic  diets,  301,  303 
Anti-rachitic    effect,   of   butter   fat, 

314 

of  calcium,  309,  315 
of  cod  liver  oil,  314 
of  phosphorus,  309,  315 
method  of  demonstrating,  322 
Anti-rachitic  substance,  301,  302 
Anti-scorbutic  value  of  milk,  effect 
of  diet  on,  344 


Anti-scorbutic   substance,   effect    of 

temperature  on,  186-192 
Appetite,    and    food    consumption, 

10,  106 
not  a  safe  guide  to  selection  of 

food,  166,  376 
Arginin,  63,  92,  94 
Arabs,  diet  of,  151,  405,  406 
physical    perfection    of,   403,   406, 

410 

Artificial  feeding  of  infants,  428 
Artificial  "protein-free  milk,"  16,  19, 

21,  24 

Aryan  hordes,  pastoral  tribes,  420 
Atwater,  3,  50 

standard  of  protein  requirement, 

51 
Auto-intoxication,  391 

Babcock,  6 

experiments  with  salt-poor  diets, 
343 

Bahamas,  diet  in,  409,  414 

Bacillus    acidophilus    in    intestinal 
tract,  391 

Bacterial    count    of    market    milks, 
151 

Balanced  diets,  new  views  concern- 
ing, 382,  383 

Banana,  dietary  properties  of,  142 

Barley  and  rye,  132 

Barlow's  disease,  193 

Basic  amino  acids,  92,  94 

Bean,  navy,   132 

soy,  dietary  properties  of,  133 

Beaumont's  views  concerning  food, 
40 

Beef  fat,  fat-soluble  A  in,  145 

Benedict,  experiments  with  low  pro- 
tein diets,  116 

Bengalese,    physical    characteristics 

of,  407 
diet  of,  158,  407 

Beri-beri,    antiquity    of,    5,    17,    18, 

199,  368 

and  rice  eating,  201,  203,  205 
catalase  content  of  tissues  in,  233, 
234 


437 


438 


INDEX 


Beri-beri,    deficiency    in     milk     of 

women  suffering  from,  337 
Eijkman's  observations  on,  201 
etiology  of,  different  theories  con- 
cerning, 199-206 
experimental,  238 
Fletcher's  observations  on,  205 
in  Labrador,  253 
in  pigeons,  32,  34 
Schaumann's      observations      on, 

203,  207 

symptoms  of,  119 
two  forms  of,  210-212 
wet    and    dry,    relation    between, 

212 

wet,  and  war  dropsy,  210 
Biological  analysis  of  foods,  26,  44, 

123,  166,  364,  368 
Biological  value  of  proteins,  103 
Birds  and  mammals,  comparison  of 
lipin-synthesizing  power  of,  243 
Bloch,  303 

on     xerophthalmia     in     children, 

249,  250 

ophthalmia  and  fat  starvation,  250 
Blood,  in  rickets,  316 
anti-scorbutic  value  of,  175 
as  a  food,  147 

sugar  content  of,  in  beri-beri,  233 
Bolted  flour,  dietary  properties  of, 

125-127 

mineral  deficiencies  of,  126 
Bone,    development    on   vegetarian 

diet,  164 
growth,    sequence    of    events    in, 

305 
histological  changes  of,  in  rickets, 

306 

rachitic,   306 
Borderline    malnutrition,    206,    216, 

217,  354 

Bottle-feeding  of  infants,  428 
Breast  feeding,  relation  of,  to  rick- 
ets, 300,  354 
Breast   milk,   diet   and   quality   of, 

352 

Buckner,  Nollau  and  Kastle,  on  ly- 
sin  content  of  chicken  feeds,  79 
Buffer  substances  in  blood,  170 
"Building-stones"  in  protein  nutri- 
tion, 91 
Butter,  21 

Butter  fat,  10,  15,  19-24,  34 
and  cod  liver  oil,  anti-rachitic  ef- 
fect of,  307 
discovery    of    peculiar    properties 

of,  20 

studies  of  McArthur  and  Luckett 
on,   247 


Calcium,  amount  required  by  rat, 

124 
and    phosphorus,    importance    of 

ratio  between,  310-313,  409 
effect  on  bones  of  deprivation  of, 

29,  315 

importance  of,  169 
in  animal  tissues,  147,  148 
Calorie,  41 
Calves,    vitality    of,    and    mother's 

diet,  7 

Carbohydrates,  1,  4 
Carbon  content  of  proteins,  91-93 
Caries,  dental,  prevention  of,  432 
Carnivorous  diet,  147,  158 

and  rickets,  317 
Carnivorous  nutrition,  examples  of, 

in  man,  389 

Carotin  and  fat-soluble  A,  261,  263 
Carrots,  dietary  properties  of,  139 
Casein,  value  of  for  growth,  99 
Cat,  absence  of  rickets  in,  318 
Cattle,  experiments  on,  6 
Cereal  grains,  as  reserve  foods,  418 
consumption  of,  and  incidence  of 

rickets,  320,  323 
cultivation  of  during  last  century, 

417,  420,  421 
deficiencies  of,  79,  80 
inadequacy   of,  for  milk  produc- 
tion, 342 

increased  consumption  of,  416-417 
little  used  by  early  peoples,  416- 

421 
proteins    of,    do    not    supplement 

each  other,  110 
proteins,  value  of,  108 
Chemical    composition,    limitations 
of  usefulness  of,  in  estimating 
food  value,  48 
Chemical    environment    of    tissues, 

383 
Chick   and  Hume,   experiments   on 

scurvy,  179-180 

Chicken  livers,  remedy  for  xeroph- 
thalmia, 249 
Chickens,  inadequacy  of  cereal  diets 

for,  79 
reared  on  diets  free  from  yellow 

pigments,  262 
Children,  food  suitable  for  young, 

399 

malnutrition  of,  217 
physical     deterioration     of,     428, 

431 
size  of  Japanese,  in  America  and 

Japan,  400 

Chinese  people,  size  of  in  north  and 
south  China,  400 


INDEX 


439 


Chittenden,     experiments     on     low 

protein  diets,  116 
standard  for  protein  requirement, 

51,  52,  386 

Chlorophyll  in  plants,  136 
Clams,  152 

Climate,  and  civilization,  408,  410 
and  rickets,  324 
depressing,  and  labor  output,  410, 

414,  415 

effects  of,  on  man,  408 
of  Japan  and  California,  402 
stimulating    effects    of,    410,    414, 

415 
versus    nutrition,    importance    of 

for  human  progress,  409 
Cleanliness     in     milk     production, 

151 

Clinic,  place   of  dental,  in  preven- 
tive dentistry,  430,  432 
Cod  liver  oil,  and  calcium  retention. 

303 

and  rickets,  303,  324 
fat-soluble  A  in,  145 
Celiac  disease,  230 
Corn  plant  ration,  experiments  on, 

6,  7 
Cottonseed  flour,  dietary  properties 

of,  79,  134 
as  human  food,  134 
Cow,  efficiency  of,  as  converter  of 

feed  into  milk,  423 
pig    and    ox,    compared    as    pro- 
ducers of  human  food,  423 
Cows,  numerical  relation  to  human 

inhabitants,  408 
Cystin,  59,  65 


Dadhi,  407 

Dairy  industry,  in  relation  to  agri- 
culture, 421 
Dairy  products,  consumption  of,  in 

Europe,  408 

Defense  barriers  and  nutrition,  383 
Deficiency  diseases,  5,  18,  173,  199, 

383 
Deficiency    diseases    seldom    occur 

uncomplicated,   213-217 
Dentistry,   preventive,  the   diet  in, 

319,  355,  431-435 
Desiccated    fruits    and    vegetables, 

188 
Deterioration,     physical,     evidences 

of,  427,  428 
Developmental  factor  in  preventive 

medicine,  432 
Diamino  acids,  93-95 
Diaphysis,  305 


Diet,  and  disease,  360 

malnutrition    among    children    in 

India,  230 

maternal  instinct,  379 
preventive  dentistry,  355 
Diet,  carnivorous,  147,  388,  419 
and  rickets,  317,  388 
causing  pellagra,  279,  282,  283 
cereal,   inadequate   for  milk  pro- 
duction, 337-338 
changes    in    American,    in   recent 

years,  416 

changes  in,  in  industrial  era,  421 
confusion  in  evaluating,  123 
effect  of,  on  outlook  on  life,  409, 

414,  415 

essential  factors  in,  34,  35,  365 
faulty,  effects  of,  on  life  history, 

55 

fruit  and  nut,  157 
human    experience    with,    dupli- 
cated with  rat  population,  373, 

374 
inducing    beri-beri,    pellagra    and 

scurvy,  214,  215 
in  the  Hebrides,  395 
in  north  and  south  China,  398 
in  pregnancy  and  nursing,   effect 

of,  on  teeth  of  child,  319 
leafy  vegetables  in  Oriental,  399 
meat,  bread  and  potato  type,  217, 

393,  399,  421 
meat,  and  rickets,  317 
method  of  evaluating,   123 
most   satisfactory  type,   171,  402, 

433 

Diet  of,  Arabs,  406 
Bahamas    and    of   lower    Canada 

contrasted,  409,  414 
children  in  Japan,  249 
Eskimo,  389 
herbivora,  317 
Icelanders,  394 
Lapps,  391 
leaf  and  seed,  162 
mother,    and    growth    of    nursing 

young,  108 
nursing  mothers,  192 
non-citizen  Indian,  390 
pastoral  peoples,  420 
primitive  man,  416,  419 
young  lions  in  captivity,  396 
Diet,  Oriental  type,  397-399 
putrefactive,     and     fermentative, 

psychic  effects  of,  391 
variety  in,  may  make  for  safety, 

402 

vegetarian,  135,  157 
Dietary  fads,  157,  386 


440 


INDEX 


Diets,    experimental,    with    nursing 

rats,  108 
vegetarian,  experiments  with,  159- 

164 
Digestion  products  of  protein,  fate 

of  after  absorption,  62 
Digestibility  of  foods,  47 
Disease  and  diet,  360 
Diseases,  communicable,  415 

milk-borne,  151 
Dogs,  rickets  in,  318 
Domestic  animals,  and  human  food, 

420 

Drummond,  36 
Dutcher,     anti-scorbutic     value     of 

milks,  344 

Early  aging,  372-374,  379 
Economy  in  purchase  of  foods,  50 
Edema,  and  wet  beri-beri,  210-212 
experimental     production     of, 

212 

Edestin,   66,  67 
Egg  yolk  fat,  fat-soluble  A  in,  19- 

20,  23,  145 
Eggs,    and    intestinal    putrefaction, 

152 

dietary  properties  of,  152,  169 
in  diet  of  pellagrins,  290 
in  Oriental  diet,  398,  399 
vitamins  in,  152 
Eijkman,  observations  on  beri-beri, 

5,  17,  18,  201,  362 
Energy  factor  in  nutrition,  43 
Energy,  rats  eat  for,  107 
Epidemic  dropsy,  210 
Epidemics  and  undernutrition,  359, 

360 

Epiphysis,  305 
Eskimo,  diet  of,  389 

free  from  rickets,  318 
Essential  factors  in  the  diet  of  rat, 

34,  35,  365 
Eutonin,   222 
Evvard,  studies  on  choice  in  feeding 

of  swine,  166 
Examples  of  successful  nutrition  on 

several  types  of  diets,  387 
Experimental  methods  in  nutrition, 

363 

results,  interpretation  of,  364 
Experiments,  length  of,  369,  370 

Famine  conditions,  malnutrition  in, 

212 

protection  against,  418 
Fasting,  does  not  induce  deficiency 

diseases,  233 


Fasting,    effect    of,    on    healing    of 

rickets,  322 
Fat   content   of  milk  as  influenced 

by  salt  starvation,  343 
Fat,  growth-promoting,  32 
Fat-soluble  A,  36 
and  keratomalacia,  368 
and  oxidation,  265 
and  stability  to  heat,  264 
and    yellow    pigments,    130,    140, 

261,  263,  366 
best  sources  of,  258,  259 
chemical  studies  on,  258 
effect    of   saponifying    agents   on, 

266 
effect  on  bones  of  deprivation  of, 

307,  312 

essential  for  maintenance,  245 
extraction  of,  from  foods  by  fat 

solvents,  265 
importance  of,  in  human  nutrition, 

251 

maize  as  a  source  of,  265 
methods  of  estimating,  267 
not  formed  by  mammary  gland, 

340 
pathological      changes      resulting 

from  lack  of,  269 
symptoms    of   specific    starvation 

for,  247 

Feces  in  experimental  diets,  77 
Feeding,    artificial,    in    relation    to 

scurvy,  192 
devices,   103 

experiments   with    purified    food- 
stuffs, 9,  10 

Ferguson,  studies  on  rickets,  300 
Fermentation,  types  of,  in  fermented 

milks,  407 

Fertility,  and  infant  mortality  as  in- 
dexes to  physiological  well-be- 
ing, 374,  379 
of  rat  as  influenced  by  nutrition, 

108,  359-374 

of  rural  and  urban  peoples,  372 
Findlay,  exercise  and  rickets,  305 
Fischer,  researches  on  proteins,  59 
Fish,  419 
Fleshy  roots,  dietary  properties  of, 

139 

Fletcher,  studies  on  beri-beri,  205 
Flour,  bolted,  dietary  properties  of, 

312 

Fluorine,  16,  25 

Food,  analysis,  chemical  and  biolog- 
ical,  3,   44,   45 
anti-scorbutic  value   of,   174,   175, 

179,   180,   185-192 
biological  analysis  of,  35 


INDEX 


441 


Food,    choice    of,    by    carnivora, 

388 

consumption  and  appetite,   107 
consumption  and  gain  in  weight, 

99,  106 

economy  in  purchase  of,  417 
human,     produced     by     different 

species  of  animals,  423 
most,  are  deficient  in  calcium,  171 
new  classification  of,  366 
of  hunting  tribes,  419 
protective,  343,  366,  433 
raw,  importance  of,  433 
requirements,  study  of,  by  statis- 
tical method,  50 
Fruits,  as  anti-scorbutic  foods,  185- 

189 

as  diuretic  foods,  141 
citrous,  as  anti-scorbutics,  141 
dietary  properties  of,  141 
juices  as  sources  of  vitamins,  141 
Funk,  17,  18,  132,  362 

studies  on  vitamins,  208,  221,  248 
Funk    and    Macallum,    studies    on 

butter  fat,  34 

Fuller's  earth  as  absorbent  for  vita- 
mins, 223 

Gelatin,  an  incomplete  protein,  59 

deficiencies  of,  59,  61,  62 
Geographic  environment   and  well- 
being,  410,  414,  415 
"Glandular"  adipose  tissue,  269 
Glandular  organs,  dietary  properties 

of,  144,  343 

source  of  fat-soluble  A,  249,  253 
supplementary  value   of  proteins 

of,  108 

vitamin  content  of,   146 
Gliadin,  lysin  in,  73 

studies  on,  66,  70 
Glutamic  acid,  In  proteins,  29 

yield  of,  by  proteins,  98 
Glycocoll,  dispensable  in  food,  65 

synthesis  of  in  body,  65 
Glyoxalase,  in  tissues  in  beri-beri, 

234 

Goiter,  in  school  girls,  422 
iodine  starvation  in,  422 
Goldberger,     studies     on     pellagra. 

274-282 

Gossypol  in  cottonseed  oil,  134 
Greens,  value  of,  as  foods,  433 
Growth,   and   maintenance,   protein 

requirement  in,  73,  85 
and  protein  consumption,  63 
capacity    for,    not    lost    through 

stunting  for  protein,  78 
element  in  vitamin  test,  236 


Growth,  experiments  with  pigs,  83 

lysin  and,  73 

nutritive  requirements  in  main- 
tenance and,  63 

vs.  maintenance,  378 

vs.  repair,  nutritional  require- 
ments for,  64 

Hart  and  Humphrey,  6 

Hart  and  Steenbock,  422 

Hart,  Steenbock  and  Ellis,  on  anti- 
scorbutic value  of  milk,  344 

Hausmann  method  for  protein  anal- 
ysis, 92 

Hebrides,  absence  of  rickets  in,  298 
diet  in,  395 

Hemeralopia,    and    deficiency    dis- 
eases, 253 
in  Brazil,  253 

Herter  and  Kendall,  experiments 
with  fermentative  and  putrefac- 
tive diets,  391 

Hess,  early  views  on  scurvy,  178 

Hess  and  linger,  on  human  require- 
ments for  fat-soluble  A,  251 
on  rickets,  303 

Hikan,  249 

Histidin,  63,  92-94 

Hog  raising,  successful  feeding  for, 
403 

Hoist,  studies  on  scurvy,  176,  362 

Hopkins,  accessory  food  factors,  22, 
248,  362 

Hormones,  62 

Horses,   size  of  island,  401 

Howland  and  Kramer,  studies  on 
blood  in  rickets,  316 

Human  and  animal  experience  with 
diets,  379,  380 

Human  experience  and  animal  ex- 
periments, 369,  435 

Human  experience  in  malnutrition, 
372 

Humidity,  optimum,  408 

Humin,  92-94 

Hunting  tribes,  food  of,  419 

Huntington   on  climate,  408-409 

Hunger  swelling,  210 

Hydroxy  pyridins,  anti-neuritic 
properties  of,  223 

Iceland,  absence  of  rickets  in,  318 

human  nutrition  in,  394 
111   health,   prevalence    of,   409-415, 

416 

Indians,  American,  diet  of,  147,  389 
Industrial  era,  diet  in,  421 
Infant  mortality  in  rats,  381 


442 


INDEX 


Infant  mortality,  and  mother's  diet, 

108 
sign  of  malnutrition,  374,  379,  381 

Infants,  bottle  feeding  of,  428 
no  suitable  food  for  weaning  to, 
in  Orient,  399 

Infanticidal  tendencies  due  to  mal- 
nutrition, 379,  382 

Insect  enemies  in  the  tropics,  411, 
413 

Intellectual  achievements,  condi- 
tions promoting,  413 

Interpretation  of  experimental  re- 
sults, 364 

Intoxication  of  intestinal  origin, 
391 

lodin,  16,  25 

in  relation  to  animal  industry,  422 
in  relation  to  goiter,  422 

Ireland,  rickets  rare  in  west  of,  298 

Island  of  Lewis,  absence  of  rickets 
in,  321 

Japanese  navy,  beri-beri  in,  17 
Jews,  once  a  pastoral  people,  404, 

420 
Jobling    and    Peterson,    studies    on 

pellagra,  277 

Johns,  protein  studies  of,  80 
Joule,     mechanical     equivalent     of 

heat,  41 

Kanehiro's  observations  on  beri- 
beri in  Japanese  navy,  200 

Kaufmann,  experiments  on  gelatin, 
61 

Kephir,  408 

Keratomalacia  and  fat-soluble  A, 
242,  247,  368 

Kidney,  value   of  proteins   of,   108 

Kitchen  middens,  153,  419 

Knapp,  observations  on  xeroph- 
thalmia,  247 

Kohlbriigge  on  fermentation  dis- 
eases, 209 

Kossel,  researches  on  proteins,  59, 
94 

Koumiss,  407 

Labor  output,  effect  of  climate  on, 

415 

Labrador,  diet  in,  253 
Lactalbumin,  studies  on,  69,  70,  75, 

79,  82,  99,  100 
supplemented     by     "protein-free 

milk,"  82 
Lactation,    sacrifice    of    mother    in, 

for  young,  343,  345 
Lacto-ovo-vegetarianism,  157 


Lactose,  See  Milk  sugar 
Lapps,  diet  of,  391 

freedom  from  rickets,  318 
Lard,  fat-soluble  A  in,  19-21,  23,  145 
Lavoisier,  41 
Leaf,  alfalfa,  135 
and  seed,  contrast  in  dietary  prop- 
erties of,  136 
corrects  deficiencies  of  seed,  160, 

161 
Leafy,  structures  of  plants,  dietary 

properties  of,  135 
vegetables,  and  Oriental  diet,  397, 

399 
consumption  of,  in  China  and 

Japan,   169 

prevention  of  scurvy  by,  171 
protective  against  pellagra,  290 
Leaves,  as  a  class  of  foods,  135 
as   source   of   fat-soluble   A,   137, 

260 
thin  and  thick,  dietary  properties 

of,  137 
Leben,  407 

Lecithin,  synthesis  of,  in  hen,  20 
Legume   seeds  and  cereals,  supple- 
mentary relations  of,   108 
Legume  seeds,  proteins  of,  132 
Lemon    juice,    confused    with   lime 

juice,   174 
Lethargy    in     carnivorous    animals 

and  man,  391 
Liebig,  41 
Life  history  as  index  to  nutrition, 

370 

Light,  effect  of,  on  rickets,  333 
of  mercury  vapor  lamp  in  treat- 
ment of  rickets,  321 
ultraviolet,  in  treatment  of  rick- 
ets, 333 
Lime  juice,  anti-scorbutic  value  of, 

174,    175 
Lion,  rickets  in,  317 

successful  rearing  of,  in  captivity, 

148,  396 
Lipin-free  diet,  studies  of,  by  Stepp, 

242,  243 

Lipins  in  diet,  20,  24 
Liver,   as   source   of  fat-soluble   A, 

249,  250,  253 
value  of  proteins  of,  108 
Low  protein  therapy,  theory  of,  52 
Lusk,  on  specific  dynamic  action  of 

foods,  42,  43'  * 
Lysin,  63,  73,  93-96 
content  of  cereals,  78 
content  of  proteins  and  their  nu- 

tritive^  values,  78 
in  gliadin,  73 


INDEX 


443 


Lysin,  in  maintenance  and  growth, 

73 

in  proteins,  73 
in  proteins  of  peanut,  134 
lacking  in  zein,  76 

Machinery    and    changes    in    food 

supply,  419 
Maintenance  and  growth,  nutritive 

requirements  during,  63 
protein  requirements  in,  23,  78 
Maintenance   experiments  with  po- 
tato nitrogen,  139 
Maintenance,  lysin  in,  73 
protein  requirements  in,  73 
vs.  growth,  378 
Maize,   amino   acid  deficiencies  of, 

81 

as  a  source  of  fat-soluble  A,  265 
gluten,  79 

kernel,  dietary  properties  of,  129 
use  of,  by  American  Indians,  416 
variation  of  fat-soluble  A  content 

of,  with  color,  259 
yellow,  130 
Malnutrition,  354,  355 
and  deficiency  diseases,  383 
borderline    conditions    of,    signifi- 
cance of,  217 
causes   destruction   of   young,   in 

rats,  379 
in  children,  431 
studies   of,   by   McCarrison,   227- 

231 

under  war  conditions,  359 
Mammary  gland,  ability  of,  to  form 

fat-soluble  A,  340 
synthesis  of  lysin  in,  74 
Man,  diet  of  primitive,  416,  419 
Manganese,  16,  25 
Manson,  observations  on  beri-beri, 

204 

Margarins,  fat-soluble  A  in,  145 
Maternal  instinct,  modified  by  diet, 

379 

Matzoon,  407 
McCarrison,    studies    on    deficiency 

diseases,  227,  231 
McCollum,      confusion      in      early 

studies,  25 
experiments   not  verified  by  Os- 

borne  and  Mendel,  15 
organic  vs.  inorganic   phosphorus 

in  nutrition,  9-12,  20,  361 
study  of  natural  foods,  26 
study    of  purified   food    mixture, 

19 

vitamins  as  impurities  in  purified 
foodstuffs,  13 


McCollum  and  Davis,  a  biological 

analysis  of  a  foodstuff,  27 
a  study  of  purified  diets,  19,  247 
hypothesis     concerning     composi- 
tion of  adequate  diet,  34 
studies  on  polished  rice,  31 
studies  on  wheat,  27,  29 
McCollum   and   Simmonds,   experi- 
ments   with    vegetarian    diets, 
162 

feeding  device  of,  103,  104 
on  life  history  of  animals,  370 
on  xerophthalmia  as  a  deficiency 

disease,  249 

McCollum,  Simmonds,  Shipley,  and 
Park,    studies    on    rickets,    305, 
307 
McKay,  on  protein  requirements  of 

Hindus,  386,  407 
Meat  eating  and  mental  attributes, 

158,   159 

Meat  eating,  arguments  against,  159 
Meat   eating  habits  of  Americans, 

393 

Meat,  and  milk  production,  423 
mineral  content  of,  110 
protective  action  in  pellagra,  290 
proteins    of,    as    supplements    to 

cereal  proteins,  110 
Meats,  anti-scorbutic  value  of,  174, 

175 

Medicine,  preventive  and  diet,  358 
"Mehlnahrschaden,"  210 
Mellanby,   studies   on   rickets,   301, 

303 

Metabolism,  endogenous  and  exog- 
enous, 63 
Metchnikoff  on  putrefaction  in  the 

intestine,  291 
Milk,  5,  21 
and  animal  tissues  compared,  149, 

150 

and  meat  production,  423 
anti-scorbutic  value  of  fresh  and 

pasteurized,  178-180 
anti-scorbutic  value  as  influenced 

by  food  of  cow,  344 
as  a  food,  149 

as  a  source  of  fat-soluble  A,  150 
as  a  supplementary  food,  149 
bacteria  in,  151 
-borne   diseases,    151 
deficient  in  iron,  149 
effect  of  faulty  diet  on  composi- 
tion of,  337,  338 
fermented,  407 
importance  of,  in  diet,  403 
manipulation    of,    decreases   anti- 
scorbutic value  of,  192 


444 


INDEX 


Milk,  mineral  content  of,  110 
non-protein  nitrogen  in,  72 
pasteurization  of,  151 
production,  cleanliness  in,  151 
importance   of  salt  supply  for, 

343 

inadequacy  of  cereals  for,  341 
of,    by    cows    on    experimental 

diets,    8 

of,  on  carnivorous  diet,  352 
protective   food   against  pellagra, 

290 
quality  falls  off  before  amount  in 

faulty  nutrition,  345 
secretion    and    growth,    food    re- 
quirements  for,  311 
soured,  as  a  food,  151,  407 
use  of,  by  Arabs,  406 
Milk  sugar  as  a  confusing  factor  in 
early  nutrition  studies,  11,   15, 
19,  20,  23,  31 
Milling    methods,    modern,     125, 

126 
Mineral  elements,  deficiencies  of,  in 

cereals,  29,  46 
essential,  1,  170 
for  milk  production,  340 
importance    of,    for   physiological 

function,  168 

importance  of,  in  foods,  168 
Millons'  reaction,  meaning  of,  59 
Minimum  requirements  of  food  fac- 
tors, 371 

Mono-amino  acids,  92-95 
Mori,  on  xerophthalmia  in  children, 

249-250,  303 
Mother,  nursing,  as  factor  of  safety 

for  young,  341 
relation  of  diet  to  quality  of  milk, 

333-338,  352 

Mouth  hygiene,  431,  432 
Munk,  on  non-protein  nitrogen  in 

milk,  72 

Muscle  and  glandular  organs,  die- 
tary properties,  contrasted,  143- 
149 

Muscle  meats,  similarity  of,  to  ce- 
real grains,  388 
vitamin  content  of,  146 


Narrow  viewpoints  of  faddists,  386 
Nervousness    due    to    malnutrition, 

380 
Nervous  symptoms  in  young  rats, 

381,  382 
Nervous  system,  instability  of,  and 

faulty  diet,  380 
New   viewpoints   in   nutrition,   361 


Night  blindness,  and  pellagra,  253 
during    Lenten    fasts    in    Russia, 

253 

in  India,  253 
in  Labrador,  253 

Nitrogen  content  of  proteins,  92,  93 
Nitrogen     retention     of     pigs     fed 

cereal  grains,  83 
Nomads,  diet  of,  151,  406 
Non-citizen    Indian,    and    tubercu- 
losis,  390 

Nucleopast  of  McCarrison,  231 
Nursing  mother,  diet  of,  352 
Nursing  mother  rat,  as  an  experi- 
mental animal,  99,  108 
Nursing  periods  of  Oriental  children, 

399,  400 

"Nutramin,"  222 
Nutrition,  effect  of  faulty  diet  on, 

369 
effect  of,  on  mental  outlook,  409, 

414,  415 
experiments   on    man,   length   of, 

53,  54 
faulty,    among    school    children, 

428-430 

faulty,  and  tuberculosis,  390 
fundamental  problems  in,  363 
human,  in  Iceland,  394 
in  preventive  medicine,  369 
new  viewpoints  in,  29,  361 
of  first  importance  in  health  work, 

383 

of  non-citizen  Indian,  390 
of  rural  and  urban  peoples,  372 
parcimony  in,  54 
physiological  economy  in,  51 
possibilities   of,   not   appreciated, 

383 

Nuts,  dietary  properties  of,  143 
fat  content  of,  143 
protein  values  of,  143 
Nyctalopia,  and  deficiency  diseases, 
253 

Oat  kernel,  amino  acid  deficiencies 

of,  80,  81 

dietary  properties  of,  130 
Oat  plant  ration  for  cows,  6,  7 
Oats,  rolled,  6,  7 
Olive  oil,  dietary  properties  of,  20, 

21,  23 

Ophthalmia,  see  Keratomalacia, 
of  dietary  origin,  248,  249 

in   Roumania,   360 
in  association  with  other  deficien- 
cy diseases,  251 

Optimal    vs.    normal    in    nutrition 
studies,  56 


INDEX 


445 


Optimal  physical  development,  383 
Organic  factor  in  bone  growth,  314 
Organic  phosphorus  in  nutrition,  9- 

12,    20,    361 

Oriental  type  of  diet,  397,  398,  399 
Oryzanin,  208,  222,  362 
Osborne,  protein  studies  of,  4,  95, 

96 

Osborne    and    Mendel,    absence    of 
water-soluble  B,  in  wheat  germ, 
136 
addition    of    inorganic    impurities 

to  experimental  diet,  24 
biological    values     of    individual 

proteins,  68,  69,  76,  99,  101 
comparison  of  value  of  individual 

proteins,  11 
confusion  as  to  factors  essential 

in  the  diet,   12,  25 
discontinuance    of    use    of    "pro- 
tein-free milk,"  67 
experiments,  with   artificial  "pro- 
tein-free milk,"  24,  25 
with  fat-free  diets,  20 
failure   to   duplicate    McCollum's 

experiments,  19 
feeding  device  of,  103 
gliadin  studies,  74 
maintenance  vs.  growth,  nutritive 

requirements  in,  73 
observations    on    butter    and    on 

butter  fat,  21-23 
observations  on  effect   of  adding 

feces  to  synthetic  diet,  77 
observations  on  lysin,  74,  75,  79 
on    food    consumption,    101,    104, 

106,  107 
on    preparation    of    "protein-free 

milk,"  16 

on  rate  of  growth  in  rat,  101 
ophthalmia  of  dietary  origin,  248 
"protein-free   milk,"  a   disturbing 
factor  in  experimental  work,  70 
studies  on,  cod  liver  oil,  145 
egg  yolk  fat,  23 
fruits,  141 
lactalbumin,  75 
legume  proteins,  132 
protein  metabolism,  67 
soy  bean,  132 
stunting      and      retention      of 

power  to   grow,  78 
vitamin  content  of  animal  tis- 
sues,  144 
Osteoblasts,  and  osteoid  production, 

305 
Osteoporosis,      conditions      causing, 

315 
Oysters,   152,   419 


Palatability  of  artificial  food  mix- 
ture,  11 

Palmer    and    Kennedy,    studies    on 
yellow  pigment  and  fat-soluble 
A,  263,  367      . 
Pasteurization  of  milk,  151 

in  relation  to  infantile  scurvy,  194 
Pastoral  nomads,  vigor  of,  404 
Pastoral  peoples,  diet  of,  151 
free  from  rickets,  323 
migration  of,  403-406,  420 
Pastoral   tribes   of   Asia,   407,   410, 

415 

of  India,  407 

Paton,  infection  in  rickets,  305 
Pea,  dietary  properties  of,  132 
Peanut,   dietary   properties   of,    134 
Pellagra,  5,  18,  408 

diets  causing,  214,  279,  282,  283 
early  history  of,  273 
experimental    production    of,    in 

animals,  191 
in  man,  279 
geographical  distribution  of,  273, 

290 

in  institutions,  278,  279 
in  nursing  infants,  287 
in  nursing  mothers,  287 
milk  and  meat,  use  of,  as  preven- 
tives of,  290 
prevented    by    satisfactory    diet, 

290 

relation  of  diet  to,  274,  278,  279 
relation  of  maize  consumption  to, 

188,  283 
similarities    of,   to   beri-beri    and 

scurvy,  289 

studies  of  Goldberger  on,  274-282 
studies   of  Jobling  and  Peterson 

on,  277 

studies   of   the    Thompson   Com- 
mission on,  276 

studies  of  Voegtlin  on,  283,  286 
symptoms  of,  273 
theories  as  to  cause  of,  273 
vitamin  preparations  in  treatment 

of,  283,  286 
vitamins  in  relation  to,  277,  283, 

286 

Pellagrins,  milk  of,  336 
Phosphorus,  effect  on  bones  of  dep- 
rivation of,  307,  315 
in  treatment  of  rickets,  324 
organic  vs^  inorganic,  9-11,  20,  361 
organic,    role    of,    in   etiology    of 

beri-beri,   207 

ratio  of,  to  calcium  in  diet,  410 
Phosphate  in  foods,  170 
Phosphorized  fats,  20 


446 


INDEX 


Physical  deterioration,  evidences  of, 

427-431 
Physiological  economy  in  nutrition, 

51 
Physical    efficiency    and    wellbeing, 

426 

Physical  perfection  of  Arabs,  406 
Pettenkofer,  42 
Pigeon  as  subject  of  vitamin  test, 

224,  226,  233,  235 

Pigmentation,  yellow  and  fat-solu- 
ble A,  366 
Pigs,  hairless,  422 
Polished  rice  and  beri-beri,  17,  18, 

400 
Pork  production,  successful  feeding 

for,  403 
Pork,  soft,  134 

Potato    nitrogen,    maintenance    ex- 
periments with,   139 
Pot  herbs,  importance   of,  in  diet, 

416 

Preservation,  effect  of,  on  anti-scor- 
butic substance,  174 
Protective  foods,  343,  352,  354,  366, 

434 

Protein,  as  limiting  factor  in  nutri- 
tion, 83 

consumption  and  growth,  67 
consumption  of,  physiological  ef- 
fects of,  386 
effect    of    plane    of    intake    on 

growth,  99 

feeding,  planning  of,  99 
high,  diet  of  Arabs,  406 
high,  not  synonymous  with  high 

meat  diet,  393 
in  nutrition,  problems  relating  to, 

60 

metabolism,  67 

nitrogen,  studies  of  potato,  139 
-poor     diet,     experiments     with, 

52 

requirements,  51 

-rich  diet,  excellent  if  well  select- 
ed, 406 
"Protein-free  milk,"  16,  20,  21,  23, 

79,  91,  101 

composition  of,  66,  72 
nitrogen  in,  70,  72,  75 
properties  of,  70 

vitiating    effects    of,    on    experi- 
ments, 66-72 

Proteins,  accurate  comparison  of  nu- 
tritive values  of,  80,  84 
amino  acids  yielded  by,  92,  98 
and  milk  production,  108 
biological  values  of,   1,  2,  4,  67, 
92 


Proteins,  biological  value  of,  meth- 
ods for  determining,  99 

cereal    and    meat,    supplementary 
relations  of,   108 

cereal    and    milk,    supplementary 
relations  of,  108 

comparison  of  nutritive  values  of, 
11,  15,  66,  67,  103 

comparative  values  of,  in  cereal 
grains,  109-115 

conditions  for  most  efficient  util- 
ization of,  102,  103 

content  of  food,  influence  of,  on 
food  consumption,  106,  107 

elementary  composition  of,  92 

errors  in  earlier  studies  of,  103 

methods  for  analysis  of,  92,  94 

most  vegetarian  diets  low  in,  169 

not  source  of  muscular  work,  60 

of  cereal   grains,   do   not  supple- 
ment each  other,  110 

of  cereals,  value  of,  108 

of  legume  seeds,  132 

of  leaf,  135 

of  milk,  as  supplement  to  cereal 
grains,   110 

of  milk,  value  of,  108 

of  nuts,  143 

of  peanut,  rich  in  lysin,  134 

of  seed,  nutritive  value  of,  85 

optimum  quantity  for  physiologi- 
cal wellbeing,  120 

relative  values  of,  103,  105 

stunting  for  lack  of,  78 

supplementary  values  of,  108 

synthesis  of,  from  amino  acids  in 
body,  60,  62 

transformation  of,  into  body  tis- 
sues, 29,  30 

value  of  one's  own  and  of  foreign 
species,  66 

yield  of  amino  acids  by,  29,  30 
Prenatal    life,     importance     of,    in 

teeth  formation,  430-435 
Preventive  medicine,  and  diet,  383 

and  nutrition,  369 
Psychic   effect  of  putrefactive   and 
fermentative    types     of    diets, 
391 

Purified   diets   in  nutrition  studies, 
8,  9,  11,  12,  362,  368 

Rat,  as  an  experimental  animal,  9, 

365 
as  test   animal   for  anti-beri-beri 

vitamin,  236 
gestation  period  of,  9 
reproduction  in,  9 
span  of  life  of,  9 


INDEX 


447 


Rations  from  single   plant  sources, 

6 
Rats,  individual  variation  in  growth 

of,  99-102 

Repair  vs.    growth,    nutritional    re- 
quirements for,  64 
Respiratory  quotient,  42 
Rest,  essential  to  wellbeing,  429 
Rice,  and  beri-beri,  17,  18,  201,  203, 

.205 

biological  analysis  of,  31,  131 
coated,  131 
polished,  131 
red,  131 
unpolished,  131 
wild,  416 

Rickets,    absence    of,    in    domestic 
cats,  299 

in  leaf  eating  animals,  164 

in  wild  animals,  299 
a  dietary  disease,  316 
and  cod  liver  oil  therapy,  303 
and  sunlight,  301,  321 
and  tooth  decay,  323 
characteristics  of  the  disease,  294 
common  in  dogs,  300 
condition  of  teeth  in,  294,  319 
diagnostic    value    of    roentgeno- 

grams,  301 

effect  of  fasting  on,  322 
effect  of  fat-soluble  A  on,  301,  303 
effect  of  nursing  on  incidence  of, 

300 

etiology  of,  300-303,  316 
experiments  on,  251 
geographical  distribution  of,  297, 

298 

historical  survey  of,  296 
housing    conditions    as    effecting, 

321 
hygienic    and    dietetic   factors    in 

etiology  of,  301 
incidence    in    breast-fed    infants, 

354 

incidence  in  Scotland,  300 
in  young  lions,  396 
prevalence  of,  in  children,  294 
rare  in  Hebrides,  320,  395 
rare  in  Iceland,  318 
rare  in  west  of  Ireland,  320 
recent  investigations  on,  307 
seasonal  variation  of,  300 
skeletal  defects  in,  294 
studies  of,  by  Findlay,  305 

by  Hess  and  Unger,  303 

by    Howland    and    Kramer    of 
blood  in,  316 

by  McCollum,  Simmonds,  Ship- 
ley and  Park,  305,  307 


Rickets,  studies  of,  by  Sherman  and 
Pappenheimer,  310,  312 
by  Paton,  305 
three    etiological    factors   in,   309, 

312,  314 

views   concerning   cause    of,   299 
X-ray  treatment  in,  324 
Rohmann,  views  on  vitamins,  246 
Root  vegetables  and  content  of  fat- 
soluble  A,  259 
Rye  and  barley,  132 

Salads,  importance  of,  in  diet,  352, 

433 
Salt  starvation,  effect   of,   on  milk 

flow,  343 
Schaumann,    studies    on    beri-beri, 

203,  207,  221,  362 
Scurvy,  5,  17,  18,  35,  362,  368 

among  infants,   of   recent   occur- 
rence, 193 

anatomical  lesions  in,  185 

and  beri-beri,  similarity  of  symp- 
toms of,  210-213 

and   pasteurization   of  milk,   178, 
179 

attributed  to  acidity  of  diet,  175, 
176 

bacterial  infection  in,  177 

beri-beri   and  pellagra,  similarity 
of  symptoms  of,  212 

Chick  and  Hume,  experiments  of, 
179-182 

classic  experiments  of  Hoist,  176 

condition  of  teeth  in,  174 

description    of    acute,    in    guinea 
pigs,  184 

early  theories  as  to  etiology  of, 
173-177 

effect    of    temperature    on    anti- 
scorbutic substance,  186-192 

first    observation    of,    in    guinea 
pigs,  176 

Hess,  early  views  of,  on,  178 

in  breast-fed  infants,  352 

in  Labrador,  253 

in  monkeys,  177 

in  relation  to  diet,  173,  209 

McCollum    and    Pitz,    mistaken 
views  of,  177 

protective  action  of  foods  in,  180- 
188 

rat  immune  to,  182 

relation    in    infants    to    type    of 
feeding,  190-195 

studies  of  Cohen  and  Mendel  on, 
184 

symptoms  of,  174 

value  of  fruits  in,  141,  142 


448 


INDEX 


Sea  foods,  dietary  properties  of,  152 
in  diet  of  primitive  man,  147 

Seed  and  leaf,  contrast  in  dietary 
properties  of,  136 

Seeds,  amino  acid  content  of,  84 
low    in    inorganic    elements,    168, 

341 
of  plants,  deficiencies  of,  26,  27 

Seidell,  silver,  vitamin  compound, 
224 

Selection  of  food,  basis  of  successful 
nutrition,  386 

Shellfish,  419 

Shell  heaps,  See  Kitchen  middens. 

Sheneena,  407 

Shipley,  Park,  McCollum  and  Sim- 
monds,  studies  on  rickets,  305- 
307 

Shore  dwellers,  food  of,  419 

Simplified  diets,  importance  of 
study  of,  166 

Skeleton,  good  growth  of,  on  cer- 
tain vegetarian  diets,  164 

Skim  milk  as  source  of  fat-soluble 
A,  251 

Slonaker,  studies  on  vegetarian 
diets,  159 

Soil,  depletion  of,  by  cereal  crops, 
421 

Sour  milk,  407,  420 

Southern  United  States,  milk  con- 
sumption in,  408 

Soy  bean,  dietary  properties  of,  133 

Specific  dynamic  action  of  food- 
stuffs, 41-43 

Specific  effect  of  nutrients,  49 

Steenbock,  6,  140,  390 
yellow  pigmentation  in  relation  to 
fat-soluble  A,  261,  263 

Stepp,   experiments   on  butter   fat, 

24,  35 
studies    on   lipin-free    diets,    242- 

245 
studies  on  vitamins,  245 

Sulphur  content  of  proteins,  92 

Sunlight  in  rickets,  321,  324 

Stunting  by  faulty  diets,  and  capa- 
city to  grow,  78 

Suzuki,  on  beri-beri,  32,  362 

Sweden  and  Switzerland,  milk  con- 
sumption in,  408 

Takaki,  studies  on  beri-beri,  17 
Teeth,  condition  of,  in  scurvy,  179 
defects  in,  428,  431 
early  development  of,  355 
in  children  with  rickets,  294,  319 
in  the  Hebrides,  395 
in  Iceland,  318,  394 


Teeth,  in  prenatal  life,  430 
of    American    and    English    chil- 
dren, 410,  415 

of  carnivorous  animals,  393 
of  Eskimo,  393 
of  non-citizen  Indian,  390 
of  primitive  man,  320 
prevalence    of    decay    in,   among 

American  children,  320 
Temperature,  optimum,  408 
Tetany,  in  young  rats,  381 

the  blood  in,  316 
Tethelin,  227 

Thomas,  on  biological  value  of  pro- 
teins, 79 
Thompson     Pellagra     Commission, 

276 
Thyroid  disease  in  calves,  colts  and 

pigs,  422 

Timidity  in  experimental  rats,  380 
Tooth  decay  and  rickets,  323 
Torulin,  222 

Tropics,  enemies  of  man  in,  411 
Tryptophan,  deficiency  of,  in  pro- 
teins, 59,  62,  65 
effects  of  lack  of,  on  mice,  62 
lacking  in  zein,  76 
Tuberculosis,  and  natural  vigor,  390 
in  Hebrides,  395 
in  Labrador,  390 
in  non-citizen  Indian,  390 
Tubers,  as  source  of  anti-scorbutic 

substance,  138 
dietary  properties  of,  138 
Turnips,  dietary  properties  of,  140 
Twilight  zone  of  malnutrition,  271 
Tyrosin,  deficiency  of,  in  proteins, 
62,  65 

Ultraviolet  rays,  effect  of,  on  anti- 
scorbutic foods,  190 
Under-feeding,  effects  of,  on  compo- 
sition of  milk,  337 
Under-nourished   children,   354,   355 
Under-nutrition  and  epidemics,  359 
Urine,  effects   of  diet   on  composi- 
tion of,  63,  64 
Urinary  calculi  in  relation  to  diet, 

253 

Utility  experiments  in  nutrition,  48 
Utilization,  misuse   of  term,  47 

Variety  of  food,  and  malnutrition, 

376 

Vegetarian  diet,  135,  416 
characteristics  of,  169 
deficiencies  in,  160-169 
difficulty    of    planning    adequate, 
161-166 


INDEX 


449 


Vegetarian  diet,  in  Orient,  164 

low  in  protein,  161-169 

Slonaker's  studies  on,  159 
Vegetarianism,  inconsistencies  in  ar- 
guments for,  157-159 

perspective    in    which    to    view, 
168 

strict,  in  man,  398 
Vitamin    A    and   yellow    pigmenta- 
tion, 129,  130 
Vitamins,  12,  17,  18,  362 

chemical  studies   of,  221-226,  233 

content  of,  in  animal  tissues,  144- 
147 

content  of,  in  different  foods,  129 

content    of,    in    glandular    organs 
and  muscle  tissue,  146 

fat-borne,   necessary   in   diet,  242 

in  butter  fat,  34 

in  eggs,  152 

in  fruit  juices,  141 

in  relation  to  pellagra,  277,  283, 
286 

method  for  testing  for  water-solu- 
ble B,  236 

nomenclature  of,  36 

not  formed  by  mammary  gland, 
340 

not  present  in  milk  when  absent 
from  diet  of  mother,  334,  335 

preparations  in  treatment  of  pel- 
lagra, 283,  286 

quantitative    estimation    of.    129, 
130 

studies  of  Funk  on,  208,  221 

three  essential  for  man,  monkey 
and  guinea  pig,  35 

two  essential  for  rat,  33,  35 

yeast  as  a  test  organism  for,  237 
Voegtlin,  studies   on  pellagra,  283, 

286 

Voit,   protein  standards   of,   3,   42, 
51 


War  edema,  210,  230 

Water-soluble  B,  36 
chemical  nature  of,  221 
destruction  of,  by  alkali,  223 
in  relation  to  appetite,  232 
yeast  as  a  test  organism  for,  237 

Water-soluble  C,  36,  37 

Wells,  on  xerophthalmia  in  Balkan 
States,  303 

Wet-nursing  in  Orient,  399 

Wheat,  6 

amino  acid  deficiencies  of,  80,  81 
biological  analysis  of,  27,  29 
bran,  properties  of,  128 
calcium  content  of,  124-127 
dietary  properties  of,  124-127 
germ,  125 

germ,  alcoholic  extract  of,  32-34 
germ,  as  source  of  water-soluble 

B,  125 

germ  oil,  injurious  effects  of,  125 
mineral  elements  of,  9,  10 
plant  ration  for  cows,  7,  8 

Willcock  and  Hopkins,  studies  on 
amino  acids  in  nutrition,  8,  62 

Winter,  agricultural  value  of,  413 

Xerophthalmia,  242,  247 

Yeast,  as  a  test  organism  for  water- 
soluble  B,  237 

growth    of,    in    purified   nutrient 
media,  237 

Yellow  maize,  130 

Yellow  pigmented  root  vegetables, 
fat-soluble  A  content  of,  139, 
140 

Yellow  plant  pigments  and  fat-solu- 
ble A,  261,  263 

Yohourt,  407 

Zein,  feeding  experiments  with,  62 
nutritive  properties  of,  62 


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